The rather patronising English joke used to be that whenever the Irish question was about to be solved, the Irish would change the question. And now, when the Irish question seemed indeed to have been solved, at least for a generation, it is the English who have changed the question.

Recklessly, casually, with barely a thought, English nationalists have planted a bomb under the settlement that brought peace to Northern Ireland and close cordiality to relations between Britain and Ireland. To do this seriously and soberly would have been bad. To do it so carelessly, with nothing more than a pat on the head and a reassurance that everything will be all right, is frankly insulting.

Just five years ago, when Queen Elizabeth became the first reigning British monarch to visit southern Ireland in a century, there was a massive sense of relief. It was not just relief that the visit went off peacefully and well. It was much deeper than that: it was relief from centuries of both British condescension and Irish Anglophobia. A long story - often nasty, sometimes merely tediously wasteful - was over. There was a dignified, decent, democratic settlement that allowed the natural warmth of a neighbourly relationship to come fully to the surface.