New British prime ministers are usually desperate to establish a close relationship with the US president. Boris Johnson has a particularly strong motive to look for support in the White House.

The prime minister has finally made good on his promise to “get Brexit done” — and a trade deal with the US is meant to be a large part of the Brexit dividend. More broadly, British foreign policy has long rested on two pillars — membership of the EU and a “special relationship” with the US. Having kicked away one pillar, you would expect the prime minister to strengthen the second.

But that is not what is happening. Instead Mr Johnson has just had a row with Donald Trump — following Britain’s decision to allow Huawei, a Chinese company, to help build the UK’s 5G telecoms network. Relations between the White House and 10 Downing Street are now so bad that Mr Johnson has had to postpone a trip to the US.