1 Introduction

Liverpool is well-known for its rich Mercantile Maritime Heritage, inscribed as one of the World Heritage Sites by UNESCO in 2004 [1]. Liverpool’s comprehensive heritage context is a manifestation of the city’s story, dating back to the eighteenth and nineteenth centuries when Liverpool was a pioneering world port city and one of global maritime mercantile importance. Stemming from this industrial maritime heritage, Liverpool was enriched with a wealth of architectural and cultural assets, having more Grade I listed buildings than any city outside of London [2]. Heritage plays a key role in sustainable development within cities and is at the forefront of redevelopment in heritage sites such as Liverpool, being both an enabler and driver of the economic, social, and environmental dimensions [3]. It is therefore of upmost importance to continue to safeguard such heritage in a growing city.

After Liverpool’s successful industrial development, its economy began to falter in the twentieth century, during the great depression in the 1930s, and later collapsed post-war due to issues with international trade. The city lost its global maritime importance, becoming a shadow of its former self, and losing almost half of its population over the next 40 years ([2], p8). However, the light within the ashes for Liverpool were the rich heritage assets it was left with, and in the early 1980s, the Merseyside Development Corporation (MDC) utilised Jesse Hartley’s Albert Dock Complex for reuse. Through this development, the MDC provided Liverpool with a new setting for combined commercial and cultural uses, catalysing a new development of growth for Liverpool ([4], p. 9–11).

Since the regeneration of the Albert Dock, Liverpool has maintained a close relationship with heritage and development. In 1999, Britain’s first urban regeneration company, Liverpool Vision, was established. This organisation has been focusing on the city's economic development. That same year, Liverpool was placed on the UK’s Tentative list for UNESCO ([1], p24–25). In 2004, the city was inscribed as a World Heritage Site (WHS) with its ‘Outstanding Universal Value’ (OUV) justified under three criteria [5]. The city’s heritage site was divided into six-character areas with surrounding ‘buffer zones’, three of these areas encompassed the waterfront and its post-industrial docklands; The Pier Head, Albert and Wapping Dock, and the Stanley Dock Conservation Area [6], Fig. 1. The next major heritage-led development along this waterfront in the late 2000s were the provocative ‘Fourth Grace’ at the Pier Head, that later became the Museum of Liverpool, and three additional buildings on Mann Island [1, p24–25].

Fig. 1
figure 1

Liverpool’s WHS, Character Areas and Buffer Zones (LCC 2009, 4), focus areas of this study include Areas 1–3

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In the last ten years, Liverpool has been regarded as less successful in its relationship with heritage and development, in particular, the Stanley Docks Conservation Area and the Liverpool Waters proposal by Peel Holdings. The initial proposal for the Liverpool Waters Scheme was viewed locally as an essential step towards restoring Liverpool to its former position on a global scale. The £5.5 billion redevelopment scheme encompasses residential, business and leisure opportunities [7, p 309]. Originally, the heights of the proposed landmark 192 m, 55-storey ‘Shanghai Tower’ and its cluster of secondary tall buildings led to UNESCO in 2011 questioning the threat of development on the surrounding OUV of the WHS [1], p35). Consequently, since its go-ahead by the Liverpool City Council (LCC) for the Liverpool Waters Scheme in 2012, the city has been on the World Heritage in Danger List [1], p17). This changed in July 2021, when a new Everton Football Stadium was approved at the historic Bramley-Moore Dock, which caused Liverpool to be delisted as a WHS and become one of three World Heritage Sites (WHSs) in the world to lose their status [71].

The rationale behind this study is to understand the critical interplay between Liverpool's heritage and development over the past four decades, in light of its recent World Heritage Site delisting, and to comprehend how existing heritage can be safeguarded and reassessed in a post-World Heritage city.

Examining this interplay post-delisting is essential as it highlights the impact of losing international policy considerations on heritage safeguarding and provides valuable insights into preventing further damage to the city's heritage values. This study seeks to determine how Liverpool can sustain and safeguard its heritage, identify additional measures that should be implemented, and reassess Liverpool's heritage in this new context. The focus of this article is a comprehensive reflection on past, present, and future urban developments along Liverpool Waterfront’s post-industrial heritage. It examines how redevelopment schemes have attempted to safeguard Liverpool’s heritage considering the Historic Urban Landscape approach and how attitudes towards heritage protection in the city have evolved over time. This study is crucial for informing future policies and strategies to effectively balance urban development and heritage conservation in Liverpool and similar heritage cities.

This article will hence analyse three major existing and on-going developments, within three of the six character-areas as originally enlisted on the World Heritage List in 2004. The urban developments in focus are the Albert Dock Complex in the 1980s, the developments at the Pier Head in the late 2000s, the present Stanley Docks Conservation Area and its future regarding the Liverpool Waters Scheme, in particular, the Everton Stadium. These sites have been chosen as they represent milestone developments along the historic waterfront and serve as case studies demonstrating the evolving relationship between heritage and development over the last 40 years.

The value of this research lies in its potential as a tool for understanding this intrinsic relationship between development and heritage, applicable to current and future WHSs on the In-danger List. Additionally, it aims to encourage Liverpool to safeguard its heritage considering the Historic Urban Landscape approach, both protecting and sustaining its heritage before further damage occurs. Post-delisting, local authorities managing the site are no longer required to consider the impact of developments on the site's OUV, focusing instead on local and national heritage management policies.

2 Background

2.1 Cultural heritage and the historic urban landscape

Cultural heritage understanding was primarily established by the 1972 UNESCO Convention Concerning the Protection of the World Cultural and Natural Heritage, known as the World Heritage Convention, and its updated Operational Guidelines. Since the World Heritage List's creation in 1972, heritage interpretation has evolved, as reflected in policy documents and the types of heritage inscribed on the UNESCO World Heritage List. Heritage includes tangible assets like monuments and cities, and intangible elements such as oral traditions and traditional crafts.

The link between heritage and communities was emphasized by the UNESCO 2003 Convention for the Safeguarding of Intangible Cultural Heritage, defining five main domains of intangible cultural heritage (ICH) [8], and the Council of Europe's 2005 Faro Convention on the Value of Cultural Heritage for Society, which includes environmental elements shaped by the interaction between people and places over time [9].

These, among other policies, introduced a more integrative and inclusive perception of heritage within cities culminating in the UNESCO Recommendation on the Historic Urban Landscape in 2011. This Recommendation broadens the definition of heritage to include ‘a site’s topography, natural features, built environment (historic and contemporary), infrastructure, open spaces, land use patterns, visual relationships, and intangible dimensions such as social and cultural practices, economic processes, and identity’ [10].

The Historic Urban Landscape approach (HUL hereafter) values the engagement of past and present communities with a place. Despite such improved comprehensive understanding, the tension between conservation and regeneration remains prominent [11]. It is often easier to resist change: conservationists may feel as though they're losing control gained through previous methods, while developers may perceive it as restricting the city beyond monuments and conservation areas. However, these approaches can instead form connections and collaboratively decide what sustainable urban development means in their specific context. As Pereira Roders puts it, “there is not one [HUL] approach but as many approaches as different contexts demand” [12, p50]. The concept of a WHS as a HUL is intriguing but largely undefined. The authenticity of a WHS at an urban scale, particularly by UNESCO standards, remains unclear. This ambiguity can conflict with local visions of a WHS, especially in cities where rapid growth is prioritized by local authorities. This presents a challenge for UNESCO regarding resource allocation for monitoring and site management and poses a political challenge in demonstrating the regime's seriousness [13].

Heritage-led urban development refers to the process of using cultural heritage as a catalyst for the revitalization and sustainable development of urban areas. It aims to integrate heritage conservation into urban planning and development strategies, thereby ensuring that heritage assets contribute to the identity, attractiveness, and liability of urban environments, while also promoting tourism and economic development [14]. However, it requires careful balancing of conservation needs with contemporary development pressures to avoid commodification or loss of heritage values [13].

Development in heritage sites could take different shapes such as adaptive reuse [15], or new interventions [16]. The introduction of high-rise buildings in heritage sites presents particular challenges. Significant examples in the UK are London and Liverpool. In London, the development of high-rise buildings in the vicinity of the Tower of London has sparked debates about the visual and contextual integrity of heritage sites [17]. Meanwhile, in Liverpool, international concerns, particularly from UNESCO, over the impact on the area's OUV due to the construction of high-rise buildings near the historic waterfront, contributed to conflicted debates and eventually to the delisting as a WHS. UNESCO's decision highlighted that the new high-rise buildings and large-scale urban interventions compromised the integrity and authenticity of the historic landscape, thereby failing to meet the criteria set for WHS [18]. In the interim, local heritage management faced challenges in balancing development pressures with conservation, reflecting the more traditional and localized approach to heritage that sometimes prioritizes current economic imperatives over historical preservation [19]. This case underscores the complexities and conflicts that can arise when global heritage standards intersect with local heritage practices and economic development goals.

A global crisis over development began with the removal of Oman's Arabian Oryx Sanctuary from UNESCO's World Heritage List in 2007. This marked the first site deletion since its inscription in 1994; however, this move was supported by Oman as the respective State Party [20]. This tension escalated significantly with the delisting of the Dresden Elbe Valley in 2009, just five years after its initial recognition in 2004. This decision was spurred by a bridge project that was viewed as detrimental to the site's OUV, given that it cut across a valley integral to the city's layout and original OUV [21].

Despite the evolution of heritage understanding and the significant impact of the HUL application and associated regulations in safeguarding heritage cities globally, scholars have highlighted deficiencies in UNESCO's system of heritage inscription and its definitions of values [22, 23]. However, as Askew (2010) noted, “most professionals and academics who critique [heritage] applications and definitions ultimately rely on the term, whether because there is no adequate alternative or because they have a key stake in the term’s preservation as a carrier for their own alternative models” [24]. Additionally, international heritage policies have been criticized for their fundamental shortcomings. They lack consistency [25], especially classifying heritage assets and their values [26]. Moreover, there is uncertainty in safeguarding OUV and conditions of authenticity and integrity, particularly in identifying heritage components that embody these qualities [27, 28]. Cultural heritage is subject to individual interpretation, and definitions like OUV, essential for WHS designation, might not encompass all inherent values, thus lacking in protective capacity [29].

In this paper, we explore Liverpool's rich heritage within the HUL approach, focusing on the critical aspects of authenticity, integrity, and OUV. Our goal is to outline how these principles can be recognized and safeguarded in the city's heritage attributes, as defined in relevant international policies, especially when heritage-led development is proposed.

2.2 Liverpool’s post world heritage context

Liverpool was listed as a World Heritage Site (WHS) by UNESCO in 2004, fulfilling three of the six possible criteria for OUV: it represented a center of innovation and technology (ii), stood as an exceptional testimony to the evolution of maritime mercantile culture in the eighteenth and nineteenth centuries (iii), and was an outstanding example of a global mercantile port city illustrating the development of international trading and cultural connections throughout the British Empire (iv) [30]. The nomination document and management plan from 2003, which advocated for this listing, held that the authenticity of its heritage was defined by the surviving urban landscape and its associated elements.

Rodwell highlights that the term 'urban landscape' was given significant attention, appearing 49 times in the nomination document [31]. The term 'historic urban landscape' was also featured, a phrase that was later adopted by UNESCO in the 2005 Vienna Memorandum and the 2011 Recommendation on the HUL. The interplay between the buildings, landscape, and historical layers is key to Liverpool’s status as a coherent and discernible heritage site. However, in the formal listing of Liverpool, all mentions of the area as a HUL were removed, shifting the focus onto the conservation state of individual docks and buildings. Given that Liverpool's WHS has been used as a test case for the UNESCO HUL Initiative, the delisting in 2021 suggests a disregard for preserving this integral relationship [32, 33], putting the 'cohesive whole' of the site at risk. To protect the existing heritage and its site, in this article, we propose that the site should be perceived and managed as a HUL, rather than isolated heritage areas.

In 2009, the Liverpool City Council (LCC) issued the 'Liverpool—Maritime Mercantile City World Heritage Site Supplementary Planning Document' (SPD) as a primary tool for managing the World Heritage Site. The document was developed in response to the joint UNESCO/ICOMOS Monitoring Mission in 2006, which expressed the need for advisory documents to guide future development within the WHS [34, 35].

Critics argue that while the SPD outlines key strategies for protecting the tangible aspects of the WHS and its six primary areas, it does not address specific challenges tied to Liverpool's unique heritage context, including environmental, cultural, and intangible aspects referenced in other guidelines [36]. This lack of recognition is evident in their evaluation of authenticity and integrity. For instance, integrity is assessed by preserving material attributes like buildings and their details, while authenticity refers to the legitimacy of surviving tangible assets and alterations. However, the 'spirit of place' and sociocultural practices, such as cultural events, are not considered part of Liverpool's heritage significance. Our study aims to broaden Liverpool's understanding of integrity and authenticity, advocating for the inclusion of both tangible and intangible heritage aspects and their collective values.

2.3 Heritage impact assessments

Since its inception in 1969, impact assessments aimed at enhancing decision-making in spatial development with objective evaluations. Yet, its neutrality has been debated [7]. In heritage, it ensures development plans respect heritage asset significance [37].

In 2010, it was proposed that Heritage Impact Assessments (HIA) would address concerns about the Liverpool Waters Scheme, which was put forth a year earlier by LCC and Peel Holdings [7, p. 309]. Later that year, both parties commissioned HIA. These assessments were subsequently criticised by English Heritage (currently Historic England), prompting a third HIA carried out by a representative of their own organisation. During this period, there was limited knowledge about HIA, with the first official document, 'Guidance on Heritage Impact Assessments for Cultural World Heritage Properties,' released by ICOMOS in 2011 [38]. The nascent state of research in this area meant that the assessment methodologies were developed on-the-go [39]. To align all three HIA approaches, they were later updated following the ICOMOS guidance. Nevertheless, these assessments led to further disagreements. The HIA conducted by Peel Holdings and LCC determined the impact of the scheme would be beneficial, whereas English Heritage concluded it would be detrimental to the WHS. In 2012, despite English Heritage's conclusions, LCC granted Outline Planning Approval based on its findings with Peel Holdings [40, 41]. This decision alarmed UNESCO, who aligned with English Heritage's findings, leading to Liverpool being placed on the In-danger List later that year [42].

These HIA-related conflicts can be linked to the concept of 'framing,' as described by Patiwael et al. They define 'framing' as parties having 'dissonant frames about a problem, its causes, and solutions,' with the outcomes potentially benefitting the assessors [7, p. 310–311]. For instance, the HIA by Liverpool City Council and Peel Holdings argued that opening the area to the public would be beneficial. However, English Heritage's HIA did not acknowledge this positive outcome.

The impact of development on heritage is often influenced by the assessor's value judgments, which may reflect their party's desired outcomes. Including a third party, such as English Heritage, could mitigate bias, making findings more trustworthy to UNESCO. Heritage attribute identification and significance interpretation are also subject to stakeholder views. For example, the Gate to Waterloo Dock was valued in one assessment but dismissed by English Heritage, which included the Leeds and Liverpool Canal instead.

HIA often have a narrow focus, limiting their utility for managing complex urban sites [43, p.64–67]. In Liverpool, the HIA addressed three visually focused impacts, considered minor given the site's complexity [40, 41]. These are: (1) impact on individual heritage attributes, (2) impact on views to landmark buildings and vistas, and (3) impact on character areas or culturally significant places. These HIA overlooked potential socio-economic impacts and the broader city context, likely due to local deprivation and council reluctance to impose strict developer restrictions [44, 45].

Similarly, Dresden's visual HIA for the proposed Waldschlößchen Bridge failed to address environmental, economic, and transport issues, overlooking alternative bridge options [46, p.16]. Recurring problems with HIA in conserving endangered WHSs include the risk of manipulated outcomes due to assessor bias, and the second concerns the identification and significance of heritage attributes during HIA. This article aims to address these shortcomings by offering an impartial and comprehensive perspective on assessing development impacts on HUL in Liverpool.

3 Material and methods

This article uses a top-down approach based on a HIA framework to assess the impact of developments on Liverpool's heritage values. Our HIA method relies on understanding the OUV criteria and the conditions of Integrity and Authenticity, incorporating elements from heritage policies. These elements, sometimes called attributes, range from urban and architectural to intangible aspects.

Our approach sets itself apart from previous methodologies by offering a comparative analysis of these diverse elements. It follows international guidelines to minimise potential assessor bias and brings clarity through precise identification and relevant significance of heritage attributes during HIA processes. The HIA devised is then utilised to evaluate the influence of three significant developments on the city's post-industrial waterfront heritage. Hence, we selected three case studies, all part of Liverpool's previously inscribed World Heritage Site: The Albert Dock Complex (1981–1988), the Pier Head Development (2007–2013), and the Stanley Docks Conservation Area, inclusive of the proposed Everton Stadium (2010–2021 +).

These cases were chosen because they collectively represent most of the city's waterfront and symbolise key stages in the city's development over four decades. The Albert Docks Complex in the 1980s, for instance, marked a turning point for the city's modern development amid economic uncertainty. The Pier Head Developments in the late 2000s showcased a period when Liverpool had recently been recognised as a WHS. The current Stanley Docks Conservation Area indicates an ambiguity in the city's heritage management, particularly due to the recent loss of WHS status connected to the planning approval for the Everton Stadium.

We gathered qualitative primary data through in-person observations and photography of the critical areas. Secondary data was collected through a comprehensive critical review of historical archives and scholarly literature. Our paper's HIA methodology assesses a development's impact on Authenticity, Integrity, and OUV. These values were re-contextualised within Liverpool and encompassed both tangible and intangible attributes. Relevant definitions were extracted from a variety of policy documents offering insightful descriptions.

Given the semi-inhabited status of the three case studies, their city location, challenges in identifying associated local communities, and the time constraints of this research, it wasn't possible to gather community perspectives in line with the top-down approach. However, this offers an opportunity for future research expansion. We instead conducted interviews with four professionals well-acquainted with the Liverpool heritage context to enrich our understanding of developmental impacts.

3.1 Heritage policy documents selection

We selected twenty-one heritage policy documents spanning from 1987 to 2023. The starting point of 1987 marks the promulgation of the Washington Charter, the first document to address the conservation of historic towns and urban areas. The range extends to the updated Operational Guidelines of 2023, Table 1.

Table 1 Selected heritage policy documents
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We conducted a thorough review of these documents with the intent of establishing a comprehensive set of definitions for OUV, as well as authenticity and integrity in relation to heritage attributes. The selection criteria for each document included its relevance to one or more of the subjects listed below. Additionally, the document must have been issued by either UNESCO, ICOMOS, or ICCROM. The latter two serve as the main advisory bodies for UNESCO. The subjects of interest in the documents include:

  • Guidance for safeguarding a heritage urban area, town, and/or city;

  • Recommendations for safeguarding OUV, as well as authenticity and integrity;

  • Insights on the interplay between heritage and sustainable development.

As a result, this research adopted a methodological approach centred around content analysis. This allows for the categorisation of a range of texts based on coding rules drawn from previous knowledge and data sources [47, 48].

Our analysis began by gathering selected documents in PDF format for a detailed content review. We conducted a straightforward content analysis by searching these PDFs without using advanced software, due to the specific context of the terms investigated. We manually categorised these terms in a spreadsheet, a method that, despite being time-consuming, produced thorough insights by allowing us to examine nuanced aspects potentially missed by automated methods. The analysis proceeded in three overlapping steps:

  1. 1.

    We identified essential phrases like authenticity, integrity, true, physical, and OUV.

  2. 2.

    We noted relevant terms, disregarding their frequency for this analysis but considering it for potential future research.

  3. 3.

    We sifted through the documents to remove non-pertinent information. The definitions we found were organised by tangible and intangible elements of historic urban landscapes, linking them to sustainability and other values for practical application in real-world heritage projects.

3.1.1 Authenticity definitions

Even though we examined twenty-one different heritage policy documents, only a handful provided useful definitions, Table 2. The following table presents the definitions we discovered for authenticity.

Table 2 Extracted definitions of authenticity
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Our examination of heritage policy documents reveals a significant gap: only five documents explicitly define 'authenticity,' highlighting a lack of consensus on conservation guidelines, as emphasized by Glendinning [49]. The 1994 Nara Document by ICOMOS offered a pivotal definition, advocating a holistic heritage view, shifting from material-centric approaches [50]. This evolution continued with ICCROM et.al., which emphasized material originality and cultural value expression through various attributes [51]. The New Zealand Charter differentiates between true value and context to provide clarifications [52]. The UNESCO 2023 Operational Guidelines further this approach by integrating tangible and intangible elements in conservation and addressing archaeological reconstruction criteria [53]. The Vienna Memorandum contributed by focusing on integrating contemporary architecture into historic contexts, promoting the understanding of the historic urban landscape, and emphasizing the need for Cultural or Visual Impact Assessments [54].

3.1.2 Integrity definitions

Our content analysis found that four documents provided definitions of integrity, as Table 3 shows.

Table 3 Extracted definitions of integrity
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The definitions of 'integrity' in heritage conservation reveal an evolving understanding that expands from focusing solely on physical aspects to encompassing a site's historical, cultural, and environmental contexts. This shift signifies a move towards recognising heritage sites' complexity and the importance of a holistic approach to conservation. While no single definition captures this concept fully, the trend towards a broader perspective reflects changing priorities in the field [51, 53, 55, 56].

3.1.3 Outstanding universal value definitions

Four documents provided definitions of OUV, including the 10-world heritage listing criteria, Table 4.

Table 4 Extracted definitions of OUV
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OUV has been defined in UNESCO’s Operational Guidelines as ‘cultural and/or natural significance which is as exceptional as to transcend national boundaries and to be of common importance for present and future generations of all humanity’ [53]. It was interesting to note that the ICOMOS Guidance on Post Trauma Recovery 2017 introduced the definitions of intangible cultural heritage elements including “rituals, narratives, skills and livelihood activities” and established links between OUV and place-making activities [57]. Moreover, ICOMOS Guidance on heritage impact assessments associated large scale projects with skylines and key views related to OUV [58].

Other heritage policy documents often reference additional key heritage values such as cultural, social, historic, identity, economic, intangible, and aesthetic values. However, this study focuses on Authenticity, Integrity, and Outstanding Universal Value (OUV). According to Alsalloum and Brown, these three values encompass most tangible and intangible elements of cultural heritage, making other values less critical for this analysis [36].

For impact assessment, seven heritage elements were used. These were extracted from the definitions Authenticity, integrity, and OUV from the tables above. We have also developed a key question for each element to address when assessing the impact of developments on the heritage context, particularly regarding heritage significance. To add another layer of synthesis to this directory, we grouped the tangible elements based on their urban and individual architectural connections. We also distinguished between intangible heritage domains (such as social practices, and rituals) and the intangible values of heritage (such as the spirit of place). The results of this synthesis are presented in the subsequent tables. It is essential to note that, while this content analysis strategy has resulted in a database that enhances our understanding of the concepts under study, the method itself is time-intensive and potentially subject to human errors [59]. These elements include:

  1. 1.

    Settings/ Context and Relations with landscape (Tangible—Urban).

    (Are the settings/context and relations to landscape affected by the development?)

  2. 2.

    Urban Fabric and Morphology (Tangible—Urban).

    (Has the urban fabric and morphology changed due to the development?)

  3. 3.

    Form and Design (Tangible—Architectural).

    (Is the form and design affected by the development?)

  4. 4.

    Historical Features and Time/period (Tangible and Intangible—Architectural).

    (Does the development change or have an effect on historical features and therefore affect the time/period of the HUL?)

  5. 5.

    Material, Substance, style/colours, traditional craftsmanship (Tangible and Intangible—Architectural and Urban).

    (Does the development change the material, substance, style/colours of the HUL?)

  6. 6.

    Continuity/Sustainability (Tangible and Intangible—Architectural and Urban).

    (Does the development change the continuity and therefore sustainability of the HUL?)

  7. 7.

    Spirit of place, social interactions, cultural diversity, pride, and commemorative attributes (Intangible—Architectural and Urban).

    (has the development impacted on the spirit of place, social interactions, cultural diversity, pride, and commemorative attributes?

The impact of each heritage element has been categorised into five levels of impact. These five levels have been taken from the ICOMOS example guide for assessing magnitude of impact. These are:

  1. 1.

    No change or added value to site/property, where the values have been safeguarded.

  2. 2.

    Negligible—slight change in value to site/ property with neutral to no adverse impact.

  3. 3.

    Minor—site/property has slightly lost value.

  4. 4.

    Moderate—site/property has moderately lost value.

  5. 5.

    Major—site/property has massively lost value.

Data was organised into a table to assess the impact of developments on the HUL of each case study over the last 40 years, identifying whether these impacts have worsened. This approach, critiquing past planning and HIA, redefined Authenticity, Integrity, and OUV specifically for Liverpool, viewing the heritage site holistically rather than as isolated entities. It emphasised visual evidence through both contemporary photographs and historical archives to objectively show impacts, alongside planning documents for future developments in the Stanley Docks Conservation Area. However, the study faces limitations, including a focus on only three case studies and the inherent challenges in documenting intangible cultural heritage. Despite photographic evidence reducing subjectivity, some level of personal interpretation in assessing HIA impacts remains.

3.2 Interview with professionals

Ethical approval for this study was obtained from the University of Liverpool, with ethical protocols including the provision of participant information sheets and the collection of written consent forms. Interviews, lasting between 30 and 60 min, were conducted via Zoom. With the interviewees' permission, these sessions were recorded for analysis. The interview framework comprised three open-ended questions aimed at gathering qualitative insights into the impact of development on Liverpool’s HUL and strategies for preserving the city’s heritage context. The questions explored:

  • The perceived impact of development on heritage values along the waterfront, including which values are most affected.

  • Recommended policy changes to protect existing heritage.

  • The potential for development and heritage to synergistically promote economic growth and cultural heritage conservation.

Despite the valuable insights gained from the experts' perspectives collected, this study has limitations due to time and resource constraints. It lacks insights from Liverpool local communities and analysis of tourism and its economic impact on heritage sites. Future research could address these gaps by incorporating views from both locals and tourists, providing a fuller picture of heritage benefits for Liverpool.

4 Background and application to case studies

4.1 Albert dock complex (adaptive reuse), 1981–1988

The Albert Dock Complex, designed by Jesse Hartley and opened in 1846 by Prince Albert, exemplifies Liverpool's maritime significance and innovative inland secure dock technology [60]. It features Hartley's distinctive monumental, homogeneous dockside warehouses constructed in granite. The complex includes five 18-m-high brick-clad warehouse stacks with cast-iron frames and various supplementary historic structures [61], Fig. 2.

Fig. 2
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Albert Dock Complex (Google Earth 2021)

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The Albert Dock remained largely unaltered until its closure, with minor bomb damage in 1941 left unrepaired. The post-war decline in port trade led to economic downturns, rendering the complex redundant by 1972 [2].

In 1981, Secretary of State for the Environment Michael Heseltine established the Merseyside Development Corporation (MDC) to regenerate Liverpool's docks. Between 1983 and 1988, docks, locks, and bridges were restored, the site landscaped, and warehouses repurposed for commercial, cultural, and retail uses [62]. Since then, no significant developments have affected the complex.

4.2 Pier head developments (museum of Liverpool and Mann Island Developments), 2007–2013

The Pier Head features three monumental historic office buildings: The Royal Liver Building (1911), the Cunard Building (1916), and the Port of Liverpool Building (1907) [63]. Designed to be the city's face to the world, the Royal Liver Building is eight storeys high, granite-clad, and of mixed style. The Cunard Building, in Italian Renaissance style, is clad in Portland stone with a horizontal palazzo shape and crowning cornice. The Port of Liverpool Building, also in Portland stone, is baroque with a copper-covered dome.

South of these buildings are the Canning and Graving docks, serving as a midpoint between the Pier Head and Albert Dock Complex. Adjacent to these docks lies Mann Island, historically surrounded by docks, and later connected to the former Manchester dock (filled in during the 1930s). Mann Island's heritage includes the three-story pilotage building (1883), the Great Western Railway Warehouse (1891), and Grayson and Ould’s Pumphouse (1885) [61].

Before Liverpool's World Heritage Inscription in 2004, Will Alsop's proposed 'Fourth Grace' was replaced by the new Museum of Liverpool and three Mann Island structures [46]. The Museum of Liverpool, designed by 3XN Architects and completed by AEW Architects (2007–2011), features a low-rise design with limestone panels to complement the Three Graces and Albert Dock [7980]. Nearby, Broadway Malyan Architects' Mann Island development (2007–2013) consists of two residential wedges and an office block, using black granite and glass to mirror the historic surroundings [64, 65], Fig. 3.

Fig. 3
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Pier Head and Mann Island (Google Earth 2021)

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4.3 Stanley docks complex (adaptive reuse) and Everton stadium (Liverpool Waters), 2010–2021+

The Stanley Docks conservation area, established in the 1840s, features notable heritage elements: the granite perimeter wall with turreted gate piers, two Hartley-designed dock warehouses (1852–1854), a lifting bridge (1930), the Stanley Hydraulic Power Centre (1854) with its Kings Pipe Chimney (1900) and granite accumulator tower (1913), and the colossal 13-storey Tobacco Warehouse by A.G. Lyster (1897–1901), once the largest brick building. Nearby, Hartley’s Granite Hexagonal Clock Tower (1847–8) and Dock Master’s Office (1848) sit between river gates into Salisbury Dock. The Bramley-Moore Dock, north of Nelson Dock, served as a coal yard and features Lyster’s Accumulator Tower and the recently demolished 20th-century transit sheds [61, p.127–128]. This area is adjacent to the Leeds and Liverpool Canal [66], with many structures listed at Grade II* or II, contributing to a distinctive urban landscape [67]. In 2010, Harcourt Development began transforming the Stanley Dock Complex, including the North Warehouse and the 1950s Rum Warehouse, with plans to develop the Tobacco and South Warehouses. Adjacent docklands, owned by Peel Holdings, are part of the Liverpool Waters Scheme [68]. Everton FC's £500m stadium proposal at Bramley-Moore Dock represents a significant future development despite UNESCO's warnings, leading to Liverpool's WHS delisting in 2021 [69]. This development marks a major shift for the area, Fig. 4.

Fig. 4
figure 4

Stanley Dock Conservation Area (Google Earth 2021)

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4.4 Heritage impact assessments on the three case study areas

The HIA were carried out on the three selected case study areas. The HIA was split into seven elements of heritage as shown in the methodology section. Each value was described through observation by studying the element pre-development and again post-development. These observations were based on visual and photographic analyses, as well as an understanding of the built and socio-cultural environments of the sites. The impact of the development was then measured based on the impact upon the three key values: Authenticity, Integrity, and OUV, as defined when Liverpool was listed on the World Heritage List.

4.4.1 Albert dock complex

In the HIA of the Albert Dock Complex adaptive reuse development, Fig. 5, it was found that overall, it has had a negligible impact on the heritage values, and it has contributed to safeguarding some values. The most significant impacts, though still minor-negligible, were changes in form and design, historical features, time/period of the area, and material, substance, style/colours, affecting the authenticity of these elements. Later additions to the warehouse structures were removed, restoring them to their original design, which impacted the authenticity and intactness of the structure's historical layers. We argue that Restoration of bomb-damaged warehouses was done with careful consideration of authentic materials and construction methods. However, the Doric-style columns on the quayside changed colour significantly, moderately impacting their authenticity.

Fig. 5
figure 5figure 5

HIA of Albert dock complex adaptive reuse. a “Aerial View, 1980” [78]. b “Aerial View, 2010” [79]. c “Map of Area Pre-development, 1950” [80]. d “Map of Area Post-development, 2021” [81]. e “North Warehouse, 1966” [82]. f Authors. “North Warehouse.” Photograph. 2021. g “Swing Bridge, 1966” [83]. h Authors. “Swing Bridge.” Photograph. 2021. i “Bomb Damage to Corner of South-east Warehouse, 1980” [84]. j Authors. “Restored Corner of South-east Warehouse.” Photograph. 2021. k “View of Albert Dock Warehouses from the Strand, 1980” [84]. l Authors. “View of Albert Dock Warehouses from the Strand.” Photograph. 2021. m “1846, Abert Dock Cheering crowds to a landing ship” [85]. n Authors. “River of light festival, people walking under the lighting circles”. Photograph. 2021.

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Some changes added value to the area, especially regarding improvements in settings/context, relationship to the city, and providing a way to safeguard heritage through new functions, ensuring the site's continuity in the city's life. Assessing the intangible aspects associated with the site, the adaptive reuse added value by continuing the site's historical role in social interactions. Historically, the users of the site (such as, travellers, workers, visitors) used to exchange goods and news, besides socially interacting. With the adaptive reuse, the site continues to be ‘an iconic’ place, not only hosting cultural institutions, but also by accommodating annual and seasonal activities and events, which has created a new type of social interactions. An example is the annual river of light festival. For further details, see the Visit Liverpool website.

4.4.2 Pier head and Mann Island

In the HIA of the Museum of Liverpool Urban Intervention development, Fig. 6, it was found that overall, it has had a minor impact on the heritage values. The most significant impacts were on the relations with landscape, urban fabric and morphology, form and design, and the time/period of the area. we found that observed that The museum's form and design contrast with the Three Graces, weakening the visual integrity of the Three Graces due to its competitive form. This modern appearance affects the time/period of the area, which was previously seen as a significant historic commerce site.

Fig. 6
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HIA of Museum of Liverpool Urban Intervention. a “Aerial View of Pier Head, 1990” [86]. b “Aerial View of Pier Head, 2020” [87]. c “Map of Area Pre-development, 1990” [88]. d “Map of Area Post-Development, 2021” [88]. e Authors. “View of the Three Graces from Ferry Terminal.” Photograph. 2021. f Authors. “View of Museum of Liverpool from Canning and Graving Dock.” Photograph. 2021. g Authors. “View of the Three Graces from Museum of Liverpool.” Photograph. 2021. h Authors. “View of the Port of Liverpool Building and Museum of Liverpool from Ferry Terminal.” Photograph. 2021. i Authors. “Materiality of Three Graces.” Photograph. 2021. j Authors. “Materiality of Museum of Liverpool.” Photograph. 2021. k “View of Pier Head from Albert Dock, 2004” [89]. l Authors. “View of Pier Head from Albert Dock.” Photograph. 2021. m “The stage as a hive of activities” [85]. Authors. “River of Light Festival on Pier Head”. Photograph. 2021. n “Fresh fruits are being sold at Georges Dock from the cargo directly to the public” [85]. o Authors. “Makers Market on the Albert Dock”. Photograph. 2021

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Likewise, the overall homogeneous rectilinear morphology of the area has been impacted by the museum's shape. The integrity of the relations between key heritage areas and views towards the Three Graces has been significantly impacted by the museum's positioning and scale. While the form may be competitive and detract from the area's time/period, its function as a museum contributes to understanding the site's historic past, potentially adding value to the OUV. Despite the change in the main function, the site encourages public engagement and represents Liverpool as a place for cultural and social interactions, continuing traditions such as the Sunday market. Therefore, the intervention development has added intangible cultural and social values to the site.

In the HIA of the Mann Island Urban Intervention Developments, Fig. 7, it was found that overall, they have had a moderate impact on the heritage values. The most significant impacts were on settings/context and relations with landscape, form and design, time/period, material, substance, style/colours, and continuity/sustainability of the historic landscape. The form, design, and materiality choices significantly affect the time/period of the area and its OUV. Additionally, the positioning has compromised the integrity of the relations between heritage areas and buildings, blocking most visual connections. The residential/commercial function of the new developments does not align well with the largely cultural and historic use of the Pier Head area. In terms of socio-cultural interactions, the intervention has disrupted the continuity of some activities, such as daily synergies. The introduction of the glass atrium at the ground floor level to safeguard visual and actual connections has not been successful, resulting in a deserted area on the northern side due to the building's size and location.

Fig. 7
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HIA of Mann Island Urban Interventions. a “View towards Mann Island, 1998” [78]. b Authors. “View towards Mann Island.” Photograph. 2021. c “Map of Area Pre-development, 1990” [90]. d “Map of Area Post-Development, 2021” [91]. e “View of Mann Island Buildings and Pier Head from the Strand” [92]. f Authors. “View of Mann Island Developments from the Strand.” Photograph. 2021. Authors. “View of the Three Graces from Museum of Liverpool.” Photograph. 2021. Authors. “View of Port of Liverpool Building and Neighbouring Mann Island Development.” Photograph. 2021. Authors. “Materiality of Three Graces.” Photograph. 2021. g Authors. “View of Mann Island Developments from Museum of Liverpool.” Photograph. 2021. h “View of Mann Island from Albert Dock, 2007” [93]. i Authors. “View of Mann Island from Albert Dock.” Photograph. 2021. j “Pier Head, office workers commuting to work by ferry” [85]. Authors. “View of Mann Island from the Strand.” Photograph. 2021

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4.4.3 Stanley Dock Conservation Area

In the HIA of the Stanley Dock Complex Adaptive Reuse development, Fig. 8, it was found that overall, it has had no change to negligible impact on the heritage values. The most significant impacts were on the urban fabric and morphology, and the form and design of the Tobacco Warehouse. Changes to the Tobacco Warehouse, including the removal and alteration of its internal structure and the addition of façade perforations for windows, affected the integrity and authenticity of the structure, although these changes were necessary due to the change in function.

Fig. 8
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HIA of Stanley Dock Complex Adaptive Reuse. a “Aerial View of Stanley Dock Complex, 2017” [94]. b “Aerial View of Stanley Dock Complex, 2021” [95]. c “Map of Stanley Dock Conservation Area, 1970” [96]. d “Map of Stanley Dock Conservation Area, 2021” [96]. e “View of Stanley Dock from Bridge, 2004” [97]. f Authors. “View of Stanley Dock from Bridge.” Photograph. 2021. g “View of Tobacco Warehouse and Bridge, 2003” [98]. h Authors. “View of Tobacco Warehouse and Bridge.” Photograph. 2021. i “View of North Warehouse, 1960” [99]. j Authors. “View of North Warehouse.” Photograph. 2021. k “View of Tobacco Warehouse, 2003” [100]. l Authors. “View of Tobacco Warehouse.” Photograph. 2021. m “Inside the warehouse. Sampling and weighting the tobacco” [85]. Authors. Inside the retrofitted apartments in the warehouse. Photograph. 2021.

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There has been some minor impact on the authenticity of certain historical features repositioned throughout the complex for decorative purposes without reference to their original use. The new function added value by investing in previously decaying historic structures, preserving the site’s identity and its significance to the OUV and its relationship to the rest of the HUL. The added value is also evident in terms of social interactions and cultural diversity, as the development provides residential spaces with communal areas for interaction. Retaining original materials, such as the inside walls, and replacing window frames with similar styles have preserved part of the sense of place.

In the HIA of the Everton Stadium Urban Intervention Development Proposal, Fig. 9, it was found that overall, it has had a minor impact on the heritage values. It was observed that the infilling of the Bramley-Moore Dock and intervention of the stadium will significantly change the Urban Fabric and Morphology of the area, and lose the intactness of the historic dock, which can be argued to have a moderate effect on the OUV of the HUL. Additionally, the transit sheds that were on the site have been lost, and there is no known acknowledgement to them in the proposal which has a moderate effect on the integrity of the area’s heritage and its continuity through time. We also argue that the site prior to the stadium intervention has little heritage value and contribution to the waterfront’s overall OUV, and the addition of the stadium is going to raise the site’s significance which can be viewed as an economic benefit to the area’s remaining heritage, such as the reuse and safeguarding of the adjacent decaying grade II listed 1883 Hydraulic Accumulator Tower. Additionally, with increased occupation of the neighbouring Liverpool Waters Site within the next decade, the site is likely to receive increased interactions over time, making it an area of high social activities.

Fig. 9
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HIA of the Everton Stadium Urban Intervention Proposal. a “Aerial View of Stanley Dock Conservation Area, 2018” [101]. b “Visualisation of Everton Stadium on Bramley Moore Dock, 2021” [102]. c “Map of Bramley Moore Dock, 1970” [103]. d “Plan of Everton Stadium, 2021” [104]. e Authors. “View of the Tobacco Warehouse.” Photograph. 2021. f “Visualisation of Everton Stadium, 2021” [105]. g “View of Accumulator Tower, 2009” [106]. h “Visualisation of Accumulator Tower and Everton Stadium, 2021” [107]. i Authors. “View of Tobacco Warehouse.” Photograph. 2021. j “Visualisation of Stadium Façade, 2021” [108]. k “View of Bramley Moore Dock, 2021” [109]. l “Visualisation of Everton Stadium, 2021” [107]. m “Salisbury Dock as an exchange center” [85]. “Visualisation of Everton Stadium, 2021” [107]

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4.5 Interviews with experts

Interviews with experts were conducted in November 2021 over Zoom. The results were divided into two key themes: the impact of development on waterfront heritage and necessary changes. These main themes were further divided into sub-themes based on secondary questions and discussions during the interviews.

4.5.1 Theme 1, impact of development on the waterfront heritage

Interviewees shared diverse opinions on the development impact on Waterfront Heritage, categorised into sub-themes: impacts on HUL values, views on the Albert Dock Complex, Pier Head, Stanley Dock Conservation Area, and high rises in buffer zones.

In regard to the values most impacted across the waterfront, it was suggested that, overall, there has been an impact on the values, though it was argued by Michael Parkinson that the OUV has not yet been destroyed, who further stated that, “the problem is new-build, rather than regeneration of heritage”. John Hinchliffe suggested that development inevitably will have an impact on heritage as “it involves some change to varying degrees”, and that the impact of development in recent years has been “beneficial, but some of them neutral, and some harmful”. Whereas interviewee Matthew Crook suggested that the harmful impacts were in relation to the connections, physically and visually.

When asked on their views of each case study, much attention was drawn towards the Pier Head and Stanley Dock Conservation area. The views on the Albert Dock Complex were largely positive, though it was argued by Dennis Rodwell that the authenticity of the structures have been damaged, and that the structures “externally may be deemed authentic, internally, less-so”. Concerning the Pier Head developments, the responses were mixed, most of the interviewees praised the developments and their contrasting design, whereas Dennis Rodwell argued that they detracted from the historic buildings and could have been placed elsewhere; likewise, Matthew Crook suggested that “the Mann Island developments were in the wrong place”.

Regarding the Stanley Dock Conservation area, most attention was drawn towards the Bramley-Moore Dock and its Everton Stadium Proposal. Most were in favour of the stadium, suggesting that the site overall had little significance and the addition of a stadium would have great benefit. An interesting point made by Michael Parkinson was that Liverpool has a history of infilling docks, stating, “it is what Liverpool has always done… so you could say, part of our heritage is to renew our infrastructure when our economy changes and needs it”. Conversely, John Hinchcliffe was strongly against the proposal and suggested it has had significant damage to heritage, asserting, “…the stadium for a football club which has involved in the infilling of the biggest dock of what was the World Heritage Site, the demolition of its last transit shed and the creation of big holes in the listed dock wall.”, additionally stating that, “the Supplementary Planning Document for the World Heritage site said there should be no more infilling of historic docks.” There were also additional points made in regard to the boundary line of the previous WHS, with Dennis Rodwell stating that, “the boundary could have been much further north of the Bramley-Moore Dock”, whereas John Hinchliffe argued that “the decision was made at the time… to include the phase of five docks which were built at one time, from Bramley-Moore Dock to Stanley Dock, and that coincided with the operation of the docks. Further north the docks were still operational and we didn’t want to constrain the operation of those docks.”

4.5.2 Theme 2, changes that are needed

When asked about the changes that are needed in Liverpool, the interviewees suggested several ways in which we can better safeguard our heritage, these sub-themes included, Quality Control, Placemaking, Management of the City, Relations with UNESCO, Lessons Learnt and Next Steps for Liverpool.

In regard to quality control, Dennis Rodwell stated that, “the UK system is fundamentally weak when it comes to historic cities, it does not have the designation, protective mechanisms, and policies that protect the urban landscape.” Additionally, he provided European cases and cities where stricter controls have proven to mutually benefit both development and heritage. As for placemaking, Michael Parkinson suggested that the city needed a clearer picture, and that placemaking was absent, it "needs to be more multi-layered (including music and football culture for example).”

Following this, concerning management of the city, Matthew Crook stated that “Planning decisions are being taken within a small number of individuals, many with a financial interest in the outcome”, additionally mentioning that there has been a loss of specialist conservation and urban design staff and that “there are no longer sufficient professionally qualified or senior people in the authority or in the city region who are able to secure good outcomes.”. John Hinchliffe also provided an interesting view on the management of the city’s heritage, that we should bring more focus to other areas and non-listed heritage and expand into a regional approach for heritage protection.

Lastly, regarding the Lessons Learnt from Liverpool and the Next Steps for the city, Matthew Crook suggested that there needs to be more oversight in regard to the planning process, and in relation to the lessons learnt he stated “The damage to the waterfront and the city centre conservation areas will be long-term. This should serve as a warning to other cities not to repeat the same mistakes, and to ensure that the Liverpool Model does not take hold in their own administrations.” Dennis Rodwell suggested that there needs to be a greater communication between key parties (UNESCO, LCC and UK Government). He suggested that “we need to be responsible and look for a positive result rather than allow the city to suffer the consequences and allow further damage”. John Hinchcliffe similarly suggested we need to come up with a new ‘badge’ for Liverpool, one that is different to UNESCO’s city of historic significance and moving forward we should see the safeguarding of heritage on a larger scale.

5 Discussions

The results from the HIAs will be discussed alongside the information provided in the interviews, using the subthemes as guidance. This discussion will then be synthesised into a closing argument for what Liverpool should do to ascertain the next steps forward in safeguarding its heritage.

The key question of this research is, how has the relationship between heritage and development in Liverpool changed over the past 40 years?

From the overall results it can be deemed that initial developments in the 1980s on the Albert Docks by the MDC have shown to respect their heritage context, tangible and intangible. Whilst they have shown to have some minor to moderate impacts on the authenticity of the original heritage, they have greatly restored what was a previously decaying, and segregated site from the city and has also set a precedent for new development in and around the waterfront. As stated by John Hinchliffe, “in itself (development) can enhance the heritage interest of a site… (development) can be used to stitch together isolated heritage… the Albert Dock was brought into the city again and it becomes part of the bigger whole”. This statement also reveals that development can be used as a tool to provide tangible connections between the HUL and invigorate existing relations between heritage attributes. Furthermore, this development has added an exceptional amount of value to the area, particularly in socio-cultural dimensions. We also need to keep in mind that this development took place in a period of great economic uncertainty, demonstrating well the mutual, and beneficial relationship that heritage and development can have.

Following the Albert Dock development, the next major waterfront developments were the Mann Island Urban Interventions in the mid-to-late 2000s, including both the Museum of Liverpool by 3XN/AEW Architects, and Mann Island Buildings by Broadway Malyan. Unlike the Albert Dock, these developments are entirely new structures, and the relationship that they have with the heritage context differ significantly. The results from the HIAs show that there is no relationship between the developments and their impact on the authenticity and integrity of existing heritage, which is understandable given that the structures do not have a physical connection to the original heritage, which could be argued is a downfall of this assessment method as this has shown to lessen the total impact on that specific element. However, what has been found to impact the site in both the HIAs, and highlighted by Matthew Crook, who stated “the location of these developments has damaged relations between existing heritage, both visually and in the way you move through them weakening the integrity of the WHS. Additionally, the contemporary forms and materials have been shown in the HIAs to have some effect on the general time/period of the area, which can be argued to weaken the OUV of the site, by drawing attention to the modern structures. However, it has been argued by Michael Parkinson that it is a case of a personal aesthetic ‘taste’, and John Hinchliffe argues the case for the Mann Island Developments that, “it is a very difficult site to develop… it’s impossible to get something to match both the Three Graces in the North and Albert Docks in the South, so the contrast works well.” Therefore, the aesthetic argument is hard to determine on new builds, while assessment shows material and form choices do have an impact, particularly on the time/period of the area and could appear to be ‘competitive’; they illustrate a continuity of historical layers through time. Therefore, in regard to the layout of the assessment it could be suggested to remove the time/period element in favour of historical continuity. Furthermore, it was found that the function of the intervention has the potential to add value/de-value the OUV of a site. For example, where the museum has the ability to demonstrate cultural significance of the area, the residential/commercial functions of Broadway Malyan’s developments do not contribute, but in-fact detract from the cultural significance.

Overall, the HIA have suggested the Pier Head developments have been found to have had some adverse impact on the HUL, with the Mann Island buildings being significantly more damaging than the Museum. Though as stated previously, urban interventions are different to adaptive reuse, and there are greater challenges, such as how the new buildings can respond to multiple existing heritage contexts which differ in appearance, contrast is a potential way to overcome this. Additionally, while the adaptive reuse of the Albert Dock was shown to improve integrity and restore connections, urban interventions on the Pier Head have demonstrated that adding new masses within the urban fabric have the potential to damage this integrity. Dennis Rodwell argued that the site became “crowded out” as a result of these developments, and instead could have been “allocated to the Princes Dock”. Determining the impact of development on heritage from these case studies is challenging, but positioning these interventions differently might have enhanced the HUL with new relationships and values. Furthermore, the museum's design and function have preserved some intangible aspects of the site.

In regard to the adaptive reuse of the Stanley Dock Complex by Harcourt Developments, there were similar patterns to the Albert Dock developments on the impact of key values. For example, some heritage elements had lost some authenticity as they needed to be relocated. This was mainly due to functional reasons, which was the same reasoning for the structural changes made to the Tobacco Warehouse. But in making these changes, the development has greatly restored value to the heritage site by making it usable again, and this has shown that heritage and development can mutually benefit each other, even after 40 years. This case study further highlights the impact differences between urban interventions; it appears to be much easier to regenerate existing structures than provide entirely new ones, and the reason for this could be that there are stricter ‘dos and don’ts’ in adaptive reuse projects, whereas the controls regarding new builds in heritage areas are much weaker. The HIA also showed that the adaptive reuse of the warehouses has added socio-cultural values to the site.

Lastly, and the most controversial case study, is the Everton Stadium Proposal. It was found in the HIA, that overall, the most significant impacts were the losses in integrity to the infilling of the dock and the effect this had in relation to the adjacent docks. However, as mentioned in the interviews, due to the low significance of the site in regard to the rest of the HUL, and the fact it was abandoned and deteriorating, the intervention of a stadium provides added value to the area. Unlike the Pier Head developments, it was found that the form, design, and choice of colours of the urban intervention respond well to the surrounding heritage, such as the Tobacco Warehouse. But unlike the Mann Island developments, it is within a large open space with few heritage structures it can contextualise to, making this design approach easier. However, there have been minor adverse effects on the heritage context due to this intervention, the most obvious being the loss of the former WHS’s largest dock, the loss of the last remaining Transit Shed, and damages made to the dock wall as mentioned by John Hinchliffe. Besides the potential adverse impact of using the site only occasionally and not introducing any interpretation elements to conserve/safeguard the site as part of Liverpool’s memory. Lastly, it was further highlighted by John Hinchliffe that the boundary line was drawn there for a reason, and the SPD in 2009 professed that there should be no further infilling of docks, so it should be questioned: why were these policies not abided to?

Overall, in regard to the change in the relationship between heritage and development over the past 40 years along the Waterfront, using these three case study areas, there has been good consideration with adaptive reuse developments, with minimal impact on the heritage context. Whereas, urban interventions have shown to have more considerable adverse effects on such heritage, and this can be due to a number of reasons, such as their positioning, but also due to the developer’s disregard for existing policies. However, to gain a better understanding of this relationship on both the waterfront, and the wider city, it would be beneficial for further case studies to be analysed to explore this relationship in more depth. In addition to investigating these case studies by paying attention to their interior designs and usages. As previously suggested, adaptive reuse developments often have stricter controls which make it easier to safeguard the heritage values, therefore should the same be done for urban interventions in HULs? A point made by Dennis Rodwell during the interview, is that many European historic cities such as Bordeaux, France, or Regensberg, Germany, have much stricter building controls and “encourage harmony” between new-builds and heritage, in a similar manner to the strict rules necessary for adaptive reuse. Therefore, we argue that the UK should consider tightening up controls, so that there is a single objective between both heritage’s safeguarding and development.

In terms of heritage impact assessments, and in light of this study's findings, we argue that they need to be revised to ensure comprehensiveness. This involves including all heritage values and their attributes, in addition to the three main criteria of authenticity, integrity, and Outstanding Universal Value (OUV). Furthermore, there is a need to recognise intangible cultural heritage, encompassing practices formerly associated with the buildings under assessment up to the present day. Elements of heritage and architectural character should also be considered to minimise subjectivity.

The de-designation of a WHS serves as a crucial warning for cities like Liverpool, emphasizing the urgent need to protect their cultural heritage. This situation underscores the importance of engaging local stakeholders and adhering to national legislation in the preservation and management of heritage sites. The findings from HIAs highlight the need for increased scrutiny on new constructions within heritage sites to ensure they complement and do not detract from the existing cultural values. National legislation also plays a critical role in safeguarding WHSs. Effective legal frameworks can provide the necessary tools to manage change within heritage contexts, ensuring that any development or conservation work maintains or enhances the site's OUV. Legislation can establish clear guidelines for HIAs, quality control measures, and the management of heritage sites, offering a structured approach to balancing development pressures with the need to preserve cultural heritage. The interviews conducted as part of the assessment process shed light on several key areas for improvement. These include enhancing quality control mechanisms to ensure that new constructions meet high standards of design and compatibility with the heritage context, improving placemaking efforts to create more vibrant and culturally rich urban spaces, and strengthening the management of the city's heritage assets to ensure their long-term preservation. Furthermore, there is a potential to mend strained relationships with international bodies such as UNESCO by demonstrating a commitment to upholding the values for which the site was initially recognized. This can involve taking concrete steps to address the concerns raised by UNESCO and showing progress in the management and conservation of heritage sites.

The case of Liverpool has provided us with a learning tool on how adaptive reuse can be successfully undertaken in a HUL. Contrary to this, it provides us with knowledge on mistakes made with new builds in HULs. To further safeguard Liverpool’s heritage, we need to highlight the HUL approach, and expand from historic city to regional scale, safeguarding the historic integrity of the wider context. In addition to considering intangible heritage elements associated with the heritage sites/building for a comprehensive assessment, as well as providing adequate interpretations of historical features if these were replaced or not from their original locations. Lastly, we need to take precedent of other case cities that have succeeded in maintaining the continuity of their historic landscapes. The continuation of this research would involve carrying this out, to provide the lessons learnt from these, and how they can be adapted for Liverpool.

Accordingly, the main findings can be summarized in Table 5 below:

Table 5 Summary of findings and discussions
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6 Conclusions

This study aimed to explore how Liverpool can safeguard its heritage following the loss of its World Heritage status and examine the evolving relationship between development and heritage over the past 40 years. The focus was on the Liverpool Waterfront due to its significant developments and rich heritage landscape. A new methodological approach, based on a literature review and adaptations from existing methodologies, was used for this research. The Heritage Impact Assessments (HIA) methodology effectively demonstrated the impact of developments on key values across various architectural and urban elements in adaptive reuse projects. However, assessing authenticity in urban interventions proved challenging, requiring deeper understanding for comprehensive evaluation. Integrity was a clear indicator of whether the relations within the Historic Urban Landscape (HUL) were preserved or weakened. Similarly, analysing the impact on Outstanding Universal Value (OUV) showed how new interventions could enhance or devalue the HUL.

Our study suggests labelling the impact assessment of an area's time period as "historical continuity" to better incorporate contemporary interventions. Additionally, a deeper understanding of the intangible domains of the Waterfront’s HUL through a bottom-up approach is needed to analyse the effects of new developments. Including more values in the assessment is necessary to understand the comprehensive impact of adaptive reuse and interventions. This study highlighted the key tangible relationships between development and heritage in Liverpool and illustrated the changes over time. These insights can inform future developments within Liverpool’s HUL, making Liverpool a model for managing other HUL sites.

Our study found that adaptive reuse projects in Liverpool have been successful, with minimal impact on heritage and with added value. In contrast, urban interventions have had an adverse impact on heritage, necessitating careful consideration for future developments. Based on the established HIA and discussions with interviewees, the study strongly advises that the careful positioning of new builds is crucial for safeguarding existing relations within the HUL and particular significance.

There is a high level of aesthetic subjectivity among developers and the public regarding new builds, with each project presenting different contextual challenges. Therefore, the study recommends further investigation of successful European and similar case studies that have balanced new builds and existing heritage areas. Understanding how these cases have appeased both parties would provide valuable insights for achieving unified objectives of sustaining heritage values and enhancing the wider built environment. These insights can then be integrated into policy implementation for UK planning control.

The study's limitations included a limited number of case studies and interviewees. Expanding this would provide a more in-depth answer to the study's aims. Additionally, further investigation of intangible heritage elements and values through community participation is needed, as well as examining the interiors of buildings.

The de-listing of Liverpool as a World Heritage site remains a complex issue. The controversial Everton Stadium proposal, while showing few impacts on the site, particularly through the infill of the largest historic dock, has the potential to provide new economic and cultural value to an abandoned area on the northern border of the listed heritage site. However, this action contradicted Liverpool's 2009 Supplementary Planning Document (SPD), which aimed to prevent further dock infill, and ignored UNESCO’s guidance that such infill would cause an irreversible loss of an attribute conveying the OUV.

While regaining World Heritage status may be unlikely based on the previous designation, Liverpool must continue to respect and conserve its history and heritage context. Liverpool’s Historic Urban Landscape has more valuable heritage to offer beyond what was previously listed. Future designations need to carefully consider these values, including both tangible and intangible heritage assets, and provide guidance on safeguarding them alongside new urban interventions and adaptive reuse proposals.

In recent years, new heritage approaches have emerged, viewing cultural heritage as a dynamic system and process rather than a static collection of objects and sites. These approaches emphasize the interconnectedness of tangible and intangible heritage, the ongoing processes that shape cultural landscapes [70], and the importance of involving local communities in heritage management [71].

New heritage perspectives are particularly relevant to our discussion, advocating for an integrative and comprehensive understanding of heritage, especially considering the HUL approach. This perspective bridges the gap between global and local views, encouraging the view of heritage sites like Liverpool’s waterfront as living, evolving entities that require adaptive management strategies to balance conservation with contemporary needs [72]. These approaches can inform future efforts to manage and protect heritage sites, particularly those on the World Heritage in Danger list, facing pressures from urban development and economic change.

Reflecting on Liverpool's experiences, some conclusions are applicable to other World Heritage cities. Successful adaptive reuse projects, such as those in Vienna, where historic buildings are revitalized as cultural and residential spaces [73], and in Bordeaux, where historic wine warehouses are transformed into modern cultural and commercial areas [74], demonstrate minimal adverse impact on heritage while adding value. However, urban interventions present greater challenges. Venice maintains strict guidelines to ensure new constructions do not disrupt its historical harmony [75]. Rigorous HIA are crucial for preserving authenticity and integrity, exemplified by Kyoto's methodologies that respect traditional buildings [76]. A holistic understanding of heritage values, incorporating both tangible and intangible aspects, is essential. Local policy recommendations should integrate international guidelines, as demonstrated by Dubrovnik's stringent regulations guiding effective conservation strategies [77]. Further research should include diverse case studies and deeper community engagement to enhance the robustness and applicability of findings.