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Between the devil and the DUP: the Democratic Unionist Party and the politics of Brexit


The Democratic Unionist Party (DUP) gained an unexpected foothold at the heart of the British political system following the 2017 UK general election. Political arithmetic compelled the then Prime Minister Theresa May to enter a Confidence and Supply Agreement with Northern Ireland’s ten DUP MPs in order to shore up her minority government. The timing of the DUP’s positioning at the UK’s constitutional centre coincided with the early phase of the Brexit process and afforded the small Northern Ireland political party a degree of influence as the UK struggled to agree the terms of its departure from the EU. This article provides some analytical clarity as to how and why the DUP unexpectedly came to play a leading role in Brexit’s complex and dramatic political theatre. Drawing on interviews with senior DUP figures, opposing political parties, civil servants and political commentators, this article demonstrates the hollowness of the DUP’s Brexit position, and points to ways in which the party’s influence over the UK’s approach to the Brexit negotiations undermined relationships in Northern Ireland between unionists and nationalists, between North and South (on the island of Ireland), and between Ireland and the UK. The research reveals that Brexit has precipitated (a return to) a disruptive Unionist politics which is defined by a profound and destabilising ontological insecurity and a fear of being ‘sold out’.

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  1. In the referendum of 2016, Leave received 44.2% of vote share in Northern Ireland (BBC News 2016b), whereas in the 2015 General and 2016 Assembly elections the DUP had received 25.7 and 29.2% respectively (BBC News 2015, 2016a) The increase to 36.0% of Northern Ireland vote share for the DUP in the 2017 General election (BBC News 2017a) was attributed by a series of senior party figures to being, at least in part, a consequence of the party’s identification with and advocacy for Brexit (interviews with author, 2018).

  2. As per the terms of the 2014 Stormont House Agreement, the Assembly Members (Reduction of Numbers) Act (Northern Ireland) 2016 reduced the number of seats in the Northern Ireland Assembly from six per constituency to five. With the number of constituencies standing at 18, this represented a reduction from 108 to 90 seats.

  3. Intended to guarantee effective power-sharing at Stormont, the ‘petition of concern’ is designed to prevent the predominance of one ‘community’ over the other. A petition of concern can be brought to the Speaker in advance of any vote in the Northern Ireland Assembly. To be accepted, it requires the signatures of 30 Members (MLAs). If a petition is successfully lodged against a particular motion, then its passage requires the assent of a weighted majority (60% of those present and voting), and of at least 40% of each of the Unionist and Nationalist designations present and voting.

  4. Though at the time of writing, there is some speculation that Johnson may be prepared to revisit a reformulated backstop in order to secure a Brexit deal (see Evershed 2019b).

  5. For example, Brexit has precipitated the establishment of #Think32, a grassroots, (avowedly) cross-community and non-party political movement, whose professed aim is to promote and encourage debate on Irish unity. An event held by the group at Belfast Waterfront Hall in January 2019 attracted an audience of some 2000 people.


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The research for this article was undertaken as part of the ESRC-funded project ES/P009441/1: ‘Between Two Unions: The Constitutional Future of the Islands after Brexit’. The authors would like to acknowledge and record their thanks for the support of the project team and the ESRC.

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Correspondence to Mary C. Murphy.

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Murphy, M.C., Evershed, J. Between the devil and the DUP: the Democratic Unionist Party and the politics of Brexit. Br Polit 15, 456–477 (2020).

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  • Brexit
  • Backstop
  • Northern Ireland
  • Democratic Unionist Party