On 6 December 1921, British and Irish negotiators signed the Anglo-Irish Treaty. It was designed to bring an end to the Irish War of Independence by giving Ireland the status of a Free State within the British Commonwealth. Clause XII created a Boundary Commission, should the six counties of the predominantly unionist Northern Ireland wish to remain under British jurisdiction and when the Commission began its work, the new Free State hoped it would transfer a number of counties and large towns to the South. The Northern Ireland establishment saw it rather as copper-fastening a unionist majority there. In the event, Northern Ireland retained six of the nine counties of the old province of Ulster. However, the new land frontier did not follow any natural boundary such as a major river. Instead, it followed centuries-old county borders, straddling communities, farms and even homes. The tensions between the unionist majority and nationalist minority exploded in the 1960s into the conflict known as ‘The Troubles’. It began over civil and housing rights for Catholics, but quickly developed into a full-scale quest by the revived Irish Republican Army (IRA) for a United Ireland. The Good Friday Agreement (GFA) ended the stalemate in 1998. The treaty artfully elaborated the conflict into a series of relationships that could be widened in order to accommodate the tangled identities of being Irish or British. Ireland dropped its constitutional claim on Northern Ireland, while Britain declared that if a majority there wanted a United Ireland, it would be facilitated. There were new cross border institutions, a new framework for British-Irish relations and a power-sharing assembly in Northern Ireland.

Dragging Northern Ireland out of the EU would mean customs and regulatory controls along the border

Military checkpoints along the border disappeared; the 1992 Single European Act had already done away with customs posts. According to the Irish government, Brexit throws all these achievements into reverse. Northern nationalists had been able to live with Northern Ireland’s status quo since the GFA gave their Irish identity political expression through these cross-border arrangements, the disappearance of a physical border and the prospect of a referendum at some stage. Dragging Northern Ireland out of the EU would mean customs and regulatory controls along the border and would disrupt a panoply of North-South cooperation which significantly depends on EU law applying on both sides of the border. The EU has accepted this analysis. In the negotiations, Britain grudgingly agreed to a so-called ‘backstop’, so that if a free trade deal, or other facilitations, failed to maintain an invisible border, then Northern Ireland would effectively remain within the single market and customs union. Before the negotiations started, the then-Taoiseach Enda Kenny also secured a promise by the EU that in the event of a United Ireland, then Northern Ireland would automatically rejoin the EU. When the political agreement around the backstop was converted into a legal text, Theresa May rejected it outright, depending as she did on the Unionist DUP party for survival. However, the Tory grassroots may not be so dependable. A YouGov poll on 18 June found that 59% of Conservative Party members would tolerate a United Ireland if that was what it took to deliver Brexit. Such unity talk unsettles the Irish government. While reunification has long been official policy, Dublin has pursued it with varying degrees of enthusiasm. Over time it was adumbrated into the folksy maxim: give us a United Ireland, dear Lord, but not just yet. Today, Dublin would prefer one step at a time, namely trying to limit the impact of Brexit both on the peace process and €65 bn in bilateral trade, instead of charging into a unity referendum.

Many in the Irish Republic worry about the cost and the prospect of ‘importing’ a barely dormant sectarian conflict …