British ambassador to US quits over leaked comments calling Trump 'inept' and 'insecure'
Darroch said in a resignation letter to the Foreign Office that the scandal made it "impossible" for him to continue representing British interests in the United States.
"Since the leak of official documents from this Embassy there has been a great deal of speculation surrounding my position and the duration of my remaining term as ambassador," Darroch wrote.
"I want to put an end to that speculation. The current situation is making it impossible for me to carry out my role as I would like," he said.
British Prime Minister Theresa May told parliament moments after Darroch's resignation that the criticism he faced was "beyond unfair and wrong".
"I think he's given honourable and good service and he should be thanked for it," she said.
The Mail on Sunday's publication of Darroch's cables set off a political firestorm in London and saw Trump launch two successive days of Twitter attacks against the envoy and May.
One of the cables called the Trump administration "uniquely disfunctional" and another characterised the US leader as "inept" and "insecure".
Trump has said his administration would no longer "deal" with Darroch and described him as a "pompous fool". He also slammed outgoing premier Theresa May's "foolish".
"The wacky Ambassador that the UK foisted upon the United States is not someone we are thrilled with, a very stupid guy," Trump tweeted Tuesday, echoing a furious barrage of insults the day before.
The scandal saw Darroch taken off the guest list of a dinner attended by Trump on Monday.
London has been scrambling to stem the damage caused by the leaked documents in which Darroch reportedly said Trump's presidency could "crash and burn" and "end in disgrace".
"We don't really believe this administration is going to become substantially more normal; less dysfunctional; less unpredictable; less faction riven; less diplomatically clumsy and inept," Darroch allegedly wrote in one dispatch.
The secret cables and briefing notes sent to the UK government from Washington were seen by the Mail newspaper.
Darroch also described during a state visit to Britain just last month, as "insecure" and "incompetent".
Trump and his team had been "dazzled" by the visit to the UK - where he was received by Queen Elizabeth II - but warned the UK might not remain "flavour of the month" because "this is still the land of America First".
He reportedly wrote that the "vicious infighting and chaos" inside the White House was "mostly true".
Darroch is one of the UK's most respected diplomats whose posting in Washington DC began in January 2016, before Trump won the presidency.
The Mail on Sunday said the memos, likely leaked by someone within the UK's civil service, cover a period beginning in 2017.
One report from 22 June saw Darroch criticise Trump's fraught foreign policy on Iran, which has prompted fears in global capitals of a military conflict, as "incoherent" and "chaotic".
He allegedly said Trump's assertion that he called off retaliatory missile strikes against the Iranian regime after a US drone was shot down because it risked killing 150 Iranians, "doesn't stand up".
"It's more likely that he was never fully on board and that he was worried about how this apparent reversal of his 2016 campaign promises would look come 2020," Darroch reportedly stated. Trump is preparing to run for election again next year for a second term as president.
The UK's Foreign Office did not deny the veracity of the memos.
"The British public would expect our ambassadors to provide ministers with an honest, unvarnished assessment of the politics in their country," a spokeswoman said.
"Their views are not necessarily the views of ministers or indeed the government," she added, noting "we pay them to be candid".
"Our team in Washington have strong relations with the White House and no doubt that these will withstand such mischievous behaviour," the spokeswoman said of the potential fallout from the leak.
Follow us on Twitter: @The_NewArab