Much of this was reflected in the turnout. Although 62.7 per cent made it to the polls (up from under 55 per cent in May’s devolved elections) enthusiasm was the lowest in the UK. Furthermore, voters in nationalist heartlands were by far the least likely to vote. For the first time in many elections, turnouts in the largely unionist east were generally higher than in the west of Northern Ireland. Participation in West Belfast (48.9 per cent) and Foyle (58.7 per cent) was the lowest anywhere.

But if the campaign was low key, the aftermath was anything but. Like the rest of the UK, Northern Ireland woke up on 24 June to a political earthquake with no evidence of emergency response planning.

All of a sudden, or so it seemed, the seismic nature of the consequences became the central political fact. Politicians at Westminster made plans for “Brexit means Brexit”. Nicola Sturgeon declared that any move to take Scotland out of the EU would be “democratically unacceptable”. In Northern Ireland, the consequences of the result were at once less obviously dramatic, yet more evidently cataclysmic. While 56 per cent of the voters opted to Remain, including majorities in four of the 11 Unionist-held Westminster constituencies, nobody, it appeared, was capable of representing that fact politically.

DUP First Minister, Arlene Foster, triumphant in May, prioritised the views of a minority in Northern Ireland, including in her own constituency, in favour of the pro-Leave majority of party and the wider UK. Deputy First Minister, Sinn Fein’s Martin McGuinness, represented a party still refusing to take its seats in Westminster and uncomfortable with negotiation within a British framework. Furthermore, the Ulster Unionists could not accept the leadership of either party in representing its complex perspective.

If the result effectively paralysed and divided the political classes, nobody, it seemed, wanted to articulate the potential constitutional consequences. Almost certainly, this reflects the magnitude of the risks and the fragility of the leadership.

At a practical, if still superficial, level, this challenge is exemplified by the transformation of the open border between both Irish jurisdictions into a unique land border between the UK the EU, making the economics of customs control and the politics of immigration both more complicated and more pressing. The real challenges of Brexit are dramatically underlined by the importance of access to European markets for Irish agriculture and food, and the cross-border structure of tourism and single markets for energy.

But far more importantly, Brexit appears to put the fundamental structure of the fragile peace process into question, by removing its central structural support. The modicum of political stability achieved in Northern Ireland since 1985, was built almost entirely on accommodations and compromises negotiated by the UK and Ireland within the European Union. Like a game of diplomatic Jenga, the edifice of political stability in Northern Ireland now teeters in a state of uncertainty.

The problem is clearest if the demands of Brexit are set against the terms of the Good Friday Agreement of 1998, itself approved in an all-Ireland referendum, including 71 per cent of an 81 per cent turnout in Northern Ireland. By establishing international law to regulate the affairs of Northern Ireland, the UK accepted the specific and unique nature of Northern Ireland within which “it is for the people of the island of Ireland alone, by agreement between the two parts respectively and without external impediment, to exercise their right of self-determination on the basis of consent, freely and concurrently given, North and South”. While Ireland accepts the constitutional basis of British sovereignty, the quid pro quo is the extension of “the birth-right of all the people of Northern Ireland to identify themselves and be accepted as Irish or British, or both, as they may so choose” to all those born in Northern Ireland, as a matter of personal choice, in perpetuity. In the context of Brexit, all of the citizens of one part of the UK remain eligible citizens of the European Union.

This principle of cross border co-operation is built into the institutions of government. Under the Agreement, the Irish government has a specific and direct right to make representations to the UK government in relation to Northern Ireland “in recognition of the Irish Government’s special interest in Northern Ireland and of the extent to which issues of mutual concern arise in relation to Northern Ireland”. This applies specifically to security co-operation “in particular, the areas of rights, justice, prisons and policing in Northern Ireland”. The Northern Ireland government has to operate with parity of esteem for the “the identity, ethos, and aspirations of both communities”. Indeed, the continued existence of the Stormont Assembly is “mutually interdependent” with the cross-border North/South Ministerial Council, where it is made clear “that one cannot successfully function without the other”.

Over the years, this interdependence of peace in Northern Ireland with British-Irish co-operation and European integration, was held up as a specific strength by both British and Irish politicians. Addressing the Irish Parliament (Oireachtas) in 1998, Tony Blair identified the purpose of the peace process as “all about belonging”. He continued: “My point is very simple. Those urges to belong, divergent as they are, can live together more easily if we, Britain and the Irish Republic, can live closer together too”. All of this, he suggested, was underpinned by European integration:

“It is 25 years since we both joined what was then the EEC. We have had different approaches to agriculture, to monetary union, to defence. But increasingly, we share a common agenda and common objectives…There is no resistance to full-hearted European co-operation wherever this brings added value to us all.”

On his “return visit” to Westminster in 2007, Irish Prime Minister Bertie Ahern responded that:

“Today our partnership in the world is expressed most especially in the European Union. Our joint membership has served as a vital catalyst for the building of a deeper relationship between our two islands. Europe forms a key part of our shared future. The European Union has acted as a potent example of a new political model that enables old enemies to become partners in progress.”

The internal fragility of the arrangements agreed in 1998, has been repeatedly underlined by events in Northern Ireland. Devolution since 2007 has faced a series of mini-crises over policing (2010), flags, parades and the Past (2013-15), paramilitarism (2015) and the sovereignty of the UK over welfare (2014-15). The crucial stabilising innovation of the Good Friday Agreement was the accommodation of divergent identities within a framework of international law and internationally agreed principles and structures, which allowed for the for the exercise of sovereignty by consent. By upending supra national authority in the UK, putting into question the framework for freedom of movement and freedom of goods and services, and reintroducing the prospect of territorial separation and borders on the island of Ireland, the Brexit referendum puts into question a fundamental element of stability, without resolving the issue of what comes next.

To date, all sides have been keen to emphasise the need to find pragmatic solutions. Theresa Villiers was swiftly replaced by James Brokenshire, a close ally of new Prime Minister Theresa May, as Secretary of State. In the meantime, there is talk of judicial reviews, and the evident problem that nobody can speak for the most vulnerable economy on these islands at a time of maximum risk. But without any clear roadmap and no clear champion, it is simply impossible to predict where this ends. The risk to the intricate tower of Jenga blocks is both clear and urgent.

This piece represents the views of the authors and not those of the Brexit blog, nor the LSE. It first appeared in the Political Studies Association’s Political Insight report and is republished here with the permission of Sage Publications.

Duncan Morrow is Lecturer and Director of Community Engagement at the Institute for Research in Social Sciences, University of Ulster.

Jonny Byrne is a Lecturer in Criminology in the School of Criminology, Social Policy and Politics at the University of Ulster.