A mock customs post is set up at Ravensdale, Co Louth, as anti-Brexit campaigners highlight concerns about the impact on trade, February, 2017. Niall Carson/Press Association. All rights reserved.

Ireland was described by the French writer Jean Blanchard in 1958 as “an island behind an island”. The phrase has regularly been used since then to indicate Ireland’s peripherality in British and European terms. As Theresa May invokes Article 50 of the Lisbon Treaty this week, Ireland is determined not to be caught in another pincer of peripherality between Europe and Britain. Ireland is determined not to be caught in another pincer of peripherality between Europe and Britain.

Ireland’s political, economic and cultural dependence on Britain that continued after formal independence started in the 1920s was only really reversed in the decades after both states joined the European communities in the 1970s. Ireland’s political elites and mass publics experienced that opening of horizons as a liberation from a suffocating post-colonial intimacy with its large neighbour.

The agreeably wider embrace of Europe established a basis of equality and respect between them which substantially facilitated the Belfast agreement on Northern Ireland in 1998, bringing an end to three decades of violent conflict. Thus European integration has run with the grain of Ireland’s liberal nationalism, affirming the longer European setting in which it sought to escape its geographical fate and assert its cultural and political one.

The contrast with a Britain still struggling to find its proper role after empire and in danger of seeing England’s union with Scotland, Northern Ireland and Wales break up in the process is stark. Ireland North and South is determined to avoid a new hard border between the UK and the EU that could reopen the conflict and hence is disinclined to follow Britain into Brexit. The UK's dual sovereignty crisis – its relationship with Europe and the future of its own union – is rapidly putting Irish reunification back on the agenda.

For the Republic, an Irish exit would represent a return to dependent insularity with no European counterweight. Northern Ireland, which voted 56-44 % to remain in the EU (although most unionists voted for Brexit), struggles with the English-majority decision to leave; its nationalists seek unique or special status to stay in or close to the EU, while its unionists are divided between uncritical loyalty to the UK-majority decision and a growing awareness of how disastrous that will be for its political and economic interests.

The UK’s dual sovereignty crisis, externally concerning the EU and internally about the future of its own union, is rapidly putting Irish reunification back onto the political agenda, unexpectedly – and with unaccustomed prudence and pragmatism compared to past irredentism. Both parts of the country are coming to see that an emerging English nationalism resenting demands for Scottish independence and probably made poorer by Brexit may no longer be prepared to meet the political and economic costs of holding the UK itself together.

This looming conjuncture is just as momentous for Ireland as for the UK itself. Brexit represents an asymmetric shock politically and economically more intense than on any other member-state of the EU. Since the border between Ireland and Northern Ireland is the only land boundary between the UK and the EU, how Brexit works out will determine whether it remains fully open, as now, or relatively securitised as it was during the troubled decades.This looming conjuncture is just as momentous for Ireland as for the UK itself.

Looking at this drama from Ireland can add an important perspective on where European integration is going to the currently dominant triumphalism of the Brexiteers and the defensive resignation of the remainers in the UK. Ireland badly needs a soft Brexit to maintain its present amicably interdependent relationship with the UK; but this will be exceedingly difficult to achieve if the UK leaves the single market and the customs union. Ireland’s strategic interest and evident preference to remain a full EU member puts it firmly in the EU 27 camp.

Ireland must be careful not to be classified as too close to the UK position before the talks begin, to avoid suspicions of pre-negotiation; and when they do, the same caution applies to a bilateral deal even if it offers constructive solutions to Brussels. Small states need to be smart in these circumstances – hence the diligent and largely successful Irish efforts to flag the difficulties involved with other EU leaders and to think tactically about when and how they are best addressed.

Ireland in an EU without the UK

Beyond that Ireland must think hard about where it should be positioned in an EU without the UK. As a small open state and economy benefiting from globalisation and liberalised markets Ireland has shared many policy platforms with the UK, notwithstanding obvious differences on agriculture, structural funds or social policy. An EU without the UK will probably be more statist, more integrationist, more prone to tax harmonisation and defence sharing than many Irish leaders and citizens would like. Put another way, Brexit opens up a debate in Ireland and throughout Europe of where the EU should now go and whether the forces that drove the Brexit decision were exceptional to the UK or symptomatic of more widely shared challenges. Put another way, Brexit opens up a debate in Ireland and throughout Europe of where the EU should now go.

The multiple crises additional to Brexit referred to by EU leaders in their Rome Declaration concerning “regional conflicts, terrorism, growing migratory pressures, protectionism and social and economic inequalities” play into this debate. They raise issues of democracy, populism and institutional design for the EU’s future.

This politicisation of integration is welcome but very difficult to channel into domestic politics, where it most needs to be heard. The links between domestic politics and the European level are too opaque and technocratic for many citizens, even though their changing approval of the EU is evidently linked to its effective outcomes. Greater mobility is one of these, appealing to those who have benefited most from globalisation; its losers prefer to close borders, protect national industry and restrict migration.

These issues are common to Europe, Ireland and Britain and will continue to animate their politics after Brexit. They are accompanied by a curious impasse between the existing national and European leaderships and political elites responsible for EU policy-making and the democratic processes which produce them. They have not articulated a coherent vision for the EU’s future, are divided politically on what it should be and are increasingly subject to north-south and east-west cleavages on how it should be organised. This politicisation of integration is welcome but very difficult to channel into domestic politics, where it most needs to be heard.

Forthcoming elections in France, Germany and Italy may help to resolve that. But even if they avoid a disintegrating spiral from a victory for populist Europhobia in France they face a huge challenge to fix the euro, boost employment, stimulate sustainable growth throughout the EU and face up to the challenges of how it can be an effective foreign policy actor in a more multipolar world.

Institutionally that will probably involve more resort to differentiated integration or multi-speeds. As the Rome Declaration puts it: “We will act together, at different paces and intensity where necessary, while moving in the same direction, as we have done in the past, in line with the Treaties and keeping the door open to those who want to join later.” From the UK’s point of view that is the rational basis for the EU’s development over the medium to long term. It is already differentiated internally by membership of the euro, Schengen and Nato. Adding other concentric circles to these outside membership, as for Norway in the European Economic Association, or Turkey in the customs union, gives the UK a potential position alongside others. But first it has to choose where it wants to be in these negotiations.

Irish Minister for Communications, Climate Action and Environment Denis Naughten,and First Minister of Scotland Nicola Sturgeon, as she looks to strengthen links between Scotland and Ireland in the wake of the Brexit vote. Niall Carson/Press Association. All rights reserved.

If the UK’s exit goes badly in diplomatic and economic terms, and especially if it leaves without agreement, political and constitutional turbulence could see an English reconsideration of the Brexit decision coming after a UK breakup. Relations between the Republic and Scotland are much better in recent times, a change of potentially great interest in Northern Ireland because of its own Scottish links. Whether all this results in a united federal Ireland in a confederation with Scotland, each in the EU and enjoying strong bilateral relationships with England and Wales outside it, remains to be seen. But it is no longer fanciful to imagine such futures between these islands and their changing unions.