Of all the issues on which Donald Trump opined so forcefully on the election trail, he was particularly strident and unusually specific about trade.

Mr Trump threatened to slap a 35 per cent import tax on Ford cars if the company moved production to Mexico; he said that he would renegotiate the North American Free Trade Agreement (Nafta) and if necessary withdraw altogether; he promised to abandon the ratification of the Trans-Pacific Partnership (TPP), a trade agreement among 12 Asia-Pacific nations; he warned that he would use every lawful presidential power, including imposing emergency tariffs, on China if it did not stop its allegedly illegal activities.

As with all his policies, Mr Trump may modify or abandon parts of this package once in office, particularly if he grasps the potential impact on the US economy of starting a fully-fledged trade war. But it may be harder to shift the mindset that clearly underlies all his suggestions: a mercantilist zero-sum view of the world in which economies are intrinsically in competition and current account deficits prima facie reflect cheating by trade partners. With the positive wealth-creating role of trade increasingly and mistakenly being dismissed by politicians, that is a deeply worrying development.