New British prime minister expected to appoint next UK ambassador to the US amid leaked memo storm

Sir Kim Darroch resigned after diplomatic memos were leaked that called President Donald Trump incompetent, inept and insecure

TOPSHOT - Britain's Prime Minister Theresa May reacts as she announces her resignation outside 10 Downing street in central London on May 24, 2019. Beleaguered British Prime Minister Theresa May announced on Friday that she will resign on June 7, 2019 following a Conservative Party mutiny over her remaining in power. / AFP / Tolga AKMEN

The next UK ambassador to the US is expected to be chosen by the new British prime minister instead of Theresa May after the the leak of private memos insulting President Donald Trump.

Sir Kim Darroch resigned on Wednesday, three days after a newspaper published his secret diplomatic memos that called Mr Trump incompetent, inept and insecure.

The leak led to the Mr Trump freezing him out of the White House and firing off tweets calling him wacky, stupid and pompous, and describing Mrs May as a fool.

Officials said Mr Darroch had hoped to ride out the storm, having received private assurances from American envoys, but Mr Trump’s repeated intervention made his position untenable.

The final straw came during a debate for the Conservative Party leadership in which the front-runner, Boris Johnson, ignored opportunities to voice support for him.

In her remaining two weeks in office, Mrs May has the chance to appoint a replacement ambassador, which usually involves a rigorous recruitment process, to thwart her replacement choosing one.

Mr Johnson, who has received the public support of Mr Trump to get the role, came under heavy criticism for failing to support Mr Darroch, which critics say left him with no option but to resign.

Foreign Office Minister Alan Duncan said on Thursday that a replacement would be appointed in the "proper way", indicating the process would not be completed by the time Mrs May steps down on July 24.

"The next ambassador will be appointed in the usual way by the prime minister on the foreign secretary's recommendation with the approval of Her Majesty the Queen," Mr Duncan told politicians.

British ambassadors are usually professional diplomats rather than political appointments. Filling overseas posts involves a formal civil service process with advertisements, applications and interviews.

Appointments are made by the prime minister on the recommendation of the foreign secretary.

It is unusual, but not unknown, for non-diplomats to become ambassadors, and some have suggested Mr Johnson as prime minister might appoint someone considered strongly pro-Brexit and friendly to Mr Trump.

On Wednesday, Mr Duncan said that his respect for Mr Johnson had "taken a serious nose dive".

"Boris Johnson, instead of supporting our ambassador, dived for cover and threw him under a bus," he said.

Mr Darroch decided to resign for the sake of his family and to allow the British embassy to continue its work.

“The current situation is making it impossible for me to carry out my role as I would like," he wrote in his resignation letter.

“Although my posting is not due to end until the end of this year, I believe in the current circumstances the responsible course is to allow the appointment of a new ambassador.”

British officials are hunting for the culprits behind the leak of Mr Darroch's confidential memos.

Mr Duncan said that the investigation had so far found no evidence that the security breach was a hack, rather than a leak.