“The current situation is making it impossible for me to carry out my role as I would like," said ambassador Kim Darroch after subjected to the public tirade from the US president.
His resignation stems from leaked confidential diplomatic cables published in a British newspaper where Darroch called the Trump administration “inept” and “uniquely dysfunctional”.
Trump vowed not to work with Darroch again, calling outgoing Prime Minister Theresa May’s policies "foolish", saying it was good that she would soon be replaced.
May put her full support behind Darroch after the leak was published.
A career diplomat, the ambassador had been in Washington DC since 2016. His term was slated to finish at the end of 2019.
"Good government depends on public servants being able to give full and frank advice," said May, expressing “great regret” that he had resigned.
"The importance of defending our values and principles, particularly when they are under pressure, is key," she added.
Other voices, other views
British prime ministerial candidates weighed in on Darroch’s resignation – although former foreign secretary Boris Johnson declined to back the diplomat during a debate on Tuesday night against his rival, the incumbent foreign secretary Jeremy Hunt.
"I don't think it was necessarily the right thing for him to do,” said Johnson of Trump’s insulting tweets. “But our relationship with the US is of fantastic importance," he added.
His rival Hunt had a more pointed response. “It should never have come to this,” he said after Darroch’s announcement. Earlier he had called Trump’s insulting outbursts “disrespectful and wrong”.
Darroch received support from politicians across the political spectrum after he resigned.
In Scotland, First Minister Nicola Sturgeon said the ambassador had been “forced out” for carrying out his duties.
"Boris Johnson's failure last night to stand up for him – and stand up to the behaviour of Donald Trump – spoke volumes," said Sturgeon, head of the Scottish National Party.
The Conservative chairman of the parliament foreign affairs committee, Tom Tugendhat, said this issue could be diplomatically damaging.
"If the UK can't protect diplomatic communications and that costs people their careers, when all they've done is to execute the wishes of the government, we will degrade the quality of our envoys, diminish our influence and weaken our country," he said.
“For the United Kingdom’s next prime minister, it is obvious that flattery and sycophancy are not enough when dealing with Trump,” Thomas Wright, a senior fellow at the Washington DC think tank Brookings Institution wrote in The Atlantic.
The Foreign Office is launching an investigation into how the confidential cables were leaked, at a time when US-UK relations are considerably strained. Although Trump and his family were welcomed to the UK last month, his erratic diplomacy, including Iran and China policies are not in line with Britain’s.
At the same time, with Brexit on the horizon, Britain has maintained it wants to improve ties between the two countries, specifically creating a bilateral free trade deal once it is finally out of the European Union.