For months now, Northern Ireland has been widely seen in the rest of the United Kingdom as the biggest stumbling block to a negotiated Brexit. The Good Friday Agreement provided for the softest of soft frontiers between the six counties that form a province of the UK and the Republic of Ireland. That frontier is now more or less invisible. But, after Brexit, the shared European Union umbrella that helped facilitate this arrangement will be gone.

Through the convoluted discussions of what might be possible – judicially, technologically, diplomatically – to keep people and lorries moving smoothly in both directions across the border, politicians in the UK – including politicians in Northern Ireland – and in the Republic insist that this particular dividing line between one jurisdiction and another deserves to be treated as a “special case”. It is, they all seem to take for granted, unique.