“We have no eternal allies, and we have no perpetual enemies. Our interests are eternal and perpetual, and those interests it is our duty to follow.” So Henry Temple, the third Viscount Palmerston, described British foreign policy in 1848, at the height of its imperial pomp. “England is a power sufficiently strong, sufficiently powerful to steer her own course.”

It is more than fanciful to imagine US president-elect Donald Trump taking his cue from the 19th century British statesman. Palmerston’s style does not quite fit the social media age. But those struggling to make sense of the blizzard of tweets that describe Mr Trump’s worldview will not miss the shared insouciance. Forget historic entanglements, alliances and enmities: after Mr Trump’s inauguration next week, the world’s most powerful nation will make its own rules. America First looks a lot like America Alone.

That, anyway, is the plan. The present open global economic system was designed by the US, but Mr Trump intends to make his own rules, starting with the repudiation of the Trans-Pacific Partnership, renegotiation of the North American Free Trade Agreement with Mexico and Canada, and the imposition of hefty duties on Chinese imports. Forget, too, nostalgia for the old geopolitical order — all that stuff about shared values and democracy. This president-elect is happy to side with Russian President Vladimir Putin against both the departing President Barack Obama and the Republican foreign policy establishment.