Yet the heart of the alliance is being hollowed out. The transatlantic relationship increasingly resembles a loveless marriage. The bills are paid (amid a lot of squabbling about who picks up which tab). The house and car are maintained. The kids are educated. There is food in the fridge. There are even regular trips abroad. But at least one side thinks privately that if not already married, they would be arranging things differently.

That is mostly, but not wholly, Mr Trump’s fault. The passage of time has worn away at the shared experiences which once fired Atlanticist spirits. Only people in their late 80s remember the Normandy landings of 1944 or the Berlin Airlift of 1948 — events which epitomise American bravery and sacrifice in liberating Europe and keeping it free.

The terrors of the Cold War are fading too: the fear that the Soviet empire might actually win, or that we might blow up the world with nuclear weapons. Even memories of the triumph of 1989-91, when the collapse of communism brought the ultimate prize for Atlanticists, of Europe whole and free, are confined to the over-40s. Instead, the millennial generation equates American leadership with failed, illegal wars and with a model of financial capitalism which nearly capsized the world economy.