When the Mail on Sunday published private assessments of the White House from the British ambassador to the United States, President Trump expressed outrage.

In a leaked cable, Ambassador Kim Darroch called the White House "inept" and "incompetent" and said the president "radiates insecurity." Trump called Darroch "stupid" and said he wouldn't deal with him.

On Wednesday, after 3 1/2 years in his post, Darroch resigned.

The episode generated outrage in London as well — not because of Darroch's criticisms, which are shared among political observers here, but because many Britons suspect someone leaked the candid assessments of a leading diplomat for political advantage.

"You were the target of a malicious leak; you were simply doing your job," Simon McDonald, permanent under secretary at the Foreign and Commonwealth Office, wrote on Wednesday to Darroch upon accepting his resignation.

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Anthony Gardner, a former U.S. ambassador to the European Union, said leaks like the ones involving Darroch's comments could damage the effectiveness of the United Kingdom and the morale of its diplomats.

"If the U.K. allows the civil service and diplomatic corps to be politicized or ... to feel that the opinions that they express are going to destroy their careers because they're out of sync with the prevailing orthodoxy, the U.K. would lose a very important asset," says Gardner.

The Foreign Office is investigating whether a member of the government leaked the diplomatic cables.

On Monday, a spokesman for Prime Minister Theresa May said there is no evidence a foreign government was involved.

The most popular theory — and it is just a theory — in the national press is that Darroch was targeted because he had supported Britain staying in the European Union and the leak would help push him out of the job before his term was to conclude at the end of this year. After Darroch's comments became public, Brexiteer politicians questioned his loyalty to the Brexit cause.

"He has an unbelievably strong commitment to us staying in the EU and that is worrying," William Cash, a Brexiteer member of Parliament in the Conservative Party, told Sky News. Cash said civil service members with views like Darroch's have trouble promoting British interests.

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AP

Boris Johnson, who is expected to win the Conservative Party leadership race later this month and become prime minister, was a leading figure in the Brexit referendum campaign three years ago. Johnson has deplored the leak, but in a TV debate Tuesday night he declined to support Darroch, which many analysts believe led to the ambassador's resignation.

Prime Minister May, on the other hand, gave a heartfelt message for the outgoing ambassador.

"It is a matter of great regret that he has felt it necessary to leave his position," she told Parliament on Wednesday. "The whole Cabinet rightly gave its full support to Sir Kim on Tuesday. Sir Kim has given a lifetime of service to the United Kingdom and we owe him an enormous debt of gratitude."

However, President Trump is a strong Brexit supporter who has criticized Prime Minister May's handling ofthe withdrawal negotiations. During his own race in 2016, he referred to himself as "Mr. Brexit," and even suggested that Nigel Farage, a key architect of the Brexit victory, would make a fine ambassador to Washington.

Darroch, by contrast, served as the U.K.'s representative to the EU from 2004 and 2007 and is widely seen as a europhile.

Farage, who is not a member of the ruling Conservative Party, suggested Darroch be fired after the contents of the cables were published.

The reporter who broke the Darroch cable story is Isabel Oakeshott, a conservative journalist with close ties to Farage and other key Brexiteers. Oakeshott insisted there was no plot.

"Sometimes a great story is just that," she wrote on Twitter, "not some kind of global conspiracy. MASSIVE eye roll."

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