Sinn Féin tells Boris Johnson he must hold Irish reunification vote should UK pursue a no-deal Brexit

Sinn Fein president Mary Lou McDonald speaking to the media with Sinn Fein Foyle MP Elisha McCallion (second from right) and Sinn Fein deputy leader Michelle O'Neill (far right). Photograph: Liam McBurney/PA Wire - Credit: PA

Sinn Féin president Mary Lou McDonald has told Boris Johnson under the terms of the Good Friday Agreement he must look to hold a referendum in the event of a no-deal Brexit.

Under the terms the incumbent Northern Ireland secretary must call a referendum on ending partition if there is evidence of a shift of public opinion in the region in favour of Irish unity.

“The way out of this for Ireland, if he is intent on crashing, if that’s the outcome, the way out for us democratically is to have a border poll and to allow Ireland and Irish people to decide our future,” she said.

McDonald accused Johnson of being “complacent” about the damage she said the “Brexit nightmare” would inflict on the island of Ireland.

“His course of action, which seems to us that he has set the compass for a disorderly and a crash Brexit, we have challenged him very strongly on that policy,” she said.

“We set out very clearly that this would be catastrophic for the Irish economy, for Irish livelihoods, for our society, for our politics and for our peace accord.

“We made it clear to him that the extensive planning he tells us he is carrying out in respect of a potential crash Brexit has to include the constitutional question and the issue of a border poll here in Ireland.

“We have stated to him very clearly that Brexit in any event, but certainly a disorderly Brexit, represents in anybody’s language a dramatic change of circumstances on this island and it would be unthinkable in those circumstances that people would not be given the opportunity to decide on our future together.”

Asked what the prime minister’s response was to her call for a border poll, the Sinn Fein leader said: “He obviously takes a different view on Brexit generally and the issue of the Union, no great surprise there.

“I have no doubt that he as a unionist and the British establishment, or elements of it, will rally against any notion of full democracy in Ireland – that position is centuries old.

“He’s not in a position to rule it out because it’s a provision of the Good Friday Agreement. He describes himself as a student of the Good Friday Agreement, he’s fully conversant with its provisions, so he has argued with us a matter of timing I would say, rather than a matter of substance.”

McDonald said any move to reintroduce direct rule at Stormont ahead of Brexit would be a “very dangerous escapade in turning the clock back”.