It is now well over three years since the UK voted, by a narrow but significant margin, to leave the European Union. Yet we still have no idea what kind of economic relationship the UK will have with the 27 countries it leaves behind. (Some of the debate in London recalls in its insularity the apocryphal 1930s headline: “Fog in Channel: Continent Cut Off.”)

Insofar as one can hazard a guess, the most likely outcome seems to be a more remote relationship than “Leave” supporters talked about in the referendum campaign and than most commentators envisaged shortly after the vote.