In the cult film The Princess Bride, the hero Westley tricks a villain, Vizzini, into killing himself in a battle of wits. Vizzini has to choose between two cups of wine, one of which Westley says is poisoned. In fact, Westley’s cup is also poisoned, but he survives: he had spent years building up immunity to the toxin. Through long and careful preparation, Westley won the battle of wits long before it had begun.

Substitute Xi Jinping for Westley and Donald Trump for Vizzini, and this week’s US-China trade talks in London make a lot more sense. They didn’t end in the US lying dead on the ground, but not far off. The sides agreed a comically vague framework of co-operation, with the US asking for a handshake to seal the deal — an activity at which Donald Trump, as it happens, is famously poor.

Nor is he much good at negotiating. Beijing is the clear winner in these early skirmishes. Trump has now lifted most of the extraordinarily punitive tariffs he has imposed on China since his inauguration. What he got back this time was China vaguely promising to lift the restrictions on rare earth exports it imposed on April 4, as plaintively requested by his chief economic adviser Kevin Hassett.