The thoughts of a British foreign secretary on world affairs are like those of a sommelier on wine – they don’t alter the taste. Boris Johnson, so often off message, was back on it today at that home of the bland, Chatham House. He gazed at the horizon and declared himself in favour of “a rules-based international order”, and against “reverting to an older and more brutal system, where the strong are free to devour the weak”. He was worried at the emergence of “non-state actors” with contempt for global liberalism. In that favourite Foreign Office phrase, he said, “We cannot allow this to happen.” Big deal, feel my muscles.

The only question just now that matters is: how is Johnson to deal with Donald Trump, insofar as he (rather than Ukip’s Nigel Farage) has influence in the new Washington DC? Here, he is all over the shop. He wants Britain to go on spending absurdly on old-fashioned defence equipment. He is in favour of Nato countries doing likewise. He is against Russia’s resumed occupation of Crimea and against it winning in Syria, except against Isis. He wants to talk with Russia, but wants to get tough with it on the Baltics. In other words Johnson wants the old Foreign Office ragbag of the unachievable in pursuit of the unacceptable, in defiance of the inevitable.

As yet, the one glimmer of hope in a Trump presidency is the indication that some of these cold war attitudes might thaw. The smart thing for Britain – and Johnson – would be to help them on their way. Why not agree with Trump’s (apparent) view that there is no “existential threat” to the west from Russia or China, and the threat from militant Islamism is criminal not cultural? Why not acknowledge that there will always be civil wars, but outside interventionists should acknowledge that they usually make them worse?

The conflicts of the current century are likely to emerge from movement of populations, not from any zest for imperial conquest. The weaponry of the cold war has become useless, trapped in a military-industrial morass. Wars of the future will be won by the machine gun and computer hackers.

Such clout as Britain might have in these matters is intellectual rather than strategic. There is no point in wailing the old nostrums about world orders. If any lesson can be drawn from the new populism, it is that they are defunct. The best Britain can do is encourage Washington to tear up the old route map and seek a new one.