For two days Sir Kim Darroch thought he was safe. When news broke that the British ambassador’s private communiqués had been leaked to a Sunday newspaper he and his senior colleagues at the embassy in Washington spoke to their contacts in the White House. Among them was Mick Mulvaney, President Donald Trump’s chief of staff.

“There were 10 or more senior people who were supportive,” said a Foreign Office source. “The chief of staff was one of them. They said it would be fine. But they also said they didn’t know what the president would do.”

Darroch hardly needed telling that. His diplomatic telegrams and classified letters home, which characterised the president’s administration as “inept” and “uniquely dysfunctional”, drew heavily on his contacts in the