A friend of mine — long separated from his wife and intent on a new life — told me that his stomach still turned over, when he opened the letter formally starting divorce proceedings. It will feel a bit like that when Britain invokes Article 50 of the Lisbon treaty, by the end of this month. The legal process of divorce from the EU will have begun and Brexit will suddenly feel real.

But the sense of certainty created by the triggering of Article 50 will, in many ways, be illusory. Brexit is still shrouded by uncertainty. As one UK official closely involved in the process puts it: “Some days I wake up and think it’s all going to be fine. Other days, it feels like a disaster in the making.”

I feel the same way. It seems to me likely that Brexit will work out badly for Britain and fairly badly for the EU. But there are so many different variables involved that nobody sensible can be sure.