Former premiers who brought about the peace process, they warned that a Leave vote may put Northern Ireland’s “future at risk” by threatening its current stability and re-open Scotland’s independence issue.
Yet the reaction of Leave campaigners at the time was one of incredulity. Theresa Villiers, the Brexit-supporting Northern Ireland Secretary, said it was “highly irresponsible” to suggest peace was at risk while Arlene Foster, who is still leader of the DUP, said that she found the intervention “rather sad”.
Such facile comments, as Mrs May tries to find a solution that rules out any possibility, however remote, of a hard border between Northern Ireland and the Republic of Ireland, show the perils of complex issues like this being over-simplified by politicians who were not even prepared to have a sensible discussion with their opponents.
And while the Prime Minister is, in fairness, encouraging Remain and Leave-supporting Tory MPs to work together to try and reach a consensus of sorts, this should have started in the immediate aftermath of the referendum two and a half years ago rather than waiting until the 11th hour.