The British ambassador the United States Kim Darroch resigned on Wednesday in the face of US President Donald Trump's fury following leaked cables in which the envoy described Trump as "inept", "insecure" and "incompetent".
Sir Kim was due to retire later this year. "History shows that there are often bespoke procedures for filling the embassy in Washington, DC", he said.
"I want all our public servants to have the confidence to be able to do that".
"I think it's very important we should have a close partnership, a close friendship with the United States", said Johnson, whom Trump has praised in the past.
But Boris Johnson - the man who will nearly certainly become Britain's prime minister when his Conservative party's leadership race concludes in July - had refused to explicitly support Darroch, dodging a question about the dispute in a televised debate Tuesday night.
McDonald said it was too soon to say what the fallout would be from the leak.
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The Cabinet Office has launched an investigation into the matter, he added.
Johnson, a former foreign minister, repeatedly failed to back Darroch during a televised debate late on Tuesday.
A day before Darroch's resignation Downing Street said he "continues to have the prime minister's full support", adding that "we have made clear to the USA how unfortunate this leak is" and that "the selective extracts leaked do not reflect the closeness of, and the esteem in which we hold, the relationship".
"I don't know the Ambassador but have been told he is a pompous fool".
He had been Britain's top diplomat in Washington since 2016, predating Trump's presidency.
Sir Kim understood that he simply couldn't do his job if he was frozen out of meetings with the President and senior White House officials.
But he said the trans-Atlantic relationship was "so deep and so wide that it will withstand any individual squall".
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Jeremy Corbyn has announced that he will demand a second European Union referendum when the next Prime Minister is in post. A group of peers have resigned the Labour whip with one claiming leader Jeremy Corbyn and "his circle" are "antisemitic".
In fact, some reports have gone so far as to suggest that pro-Brexit politicians in United Kingdom are working in cahoots with Trump minions in Washington to purge career British officials who do not toe the Trexit-Brexit line that is broadly aimed at reversing the globalisation that has put the long-privileged and porly-educated nativist and isolationist bases at a disadvantage.
"Friends speak frankly so I will: these comments are disrespectful and wrong to our Prime Minister and my country".
The First Minister of Scotland Nicola Sturgeon tweeted that it was "shameful" the diplomat had "effectively been forced out".
Sir Alan, another Hunt supporter, said Mr Johnson was an "utter wimp when the crunch comes when he should be making a stand".
"He (Boris Johnson) has basically thrown this fantastic diplomat under the bus to serve his own personal interests".
"It's hard to describe just how big a blow to our diplomatic standing in the world this resignation represents", tweeted Tom Watson, the deputy leader of the opposition Labor party.
Julie Pace contributed from Washington.
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