Cemented on the beaches of Dunkirk 75 years ago, the ‘special relationship’ between the US and UK had grown and flourished over the decades until the document leak.
Regarded as the UK’s closet ally, the US has long enjoyed a good friendship with Britain and just last week its request for its forces to detain an Iranian oil tanker in Gibraltar was executed in scenes worthy of a Hollywood movie. .
But the diplomatic row over leaked secret memos from the UK ambassador to the US has rocked the lynchpin of the transatlantic relationship.
The hot-headed Mr Trump is renown for his spats on Twitter but over the last few days his cut-throat criticism of the British prime minster Theresa May saw him tell his 62m followers she was “foolish” and her attempt to deliver Brexit has been a “disaster” – a stark contrast in tone to his state visit last month where he said she was “doing a good job”.
In a more personal outburst, he tweeted that Mr Darroch was “wacky, a stupid fool and pompous” and said he was “no longer” welcome.
The consequences of offending Washington’s first family rolled out immediately as Mr Darroch was frozen out of key meetings with Ivanka Trump and a dinner with the Emir of Qatar.
Later key post-Brexit trade talks between the US Commerce Secretary Wilbur Ross and UK trade minster Liam Fox were cancelled.
Mr Trump’s announcement that Mr Darroch is “no longer” welcome came as little surprise.
For three years the US president has been trying to influence UK politics by suggesting Brexiteer Nigel Farage should be given the job.
The right-wing politician, and now leader of the Brexit Party, has long courted a private relationship with the president. Mr Farage has long campaigned for Britain to leave the EU and for the US the benefits of having trade deals with the UK are huge.
In 2016 Mr Trump tweeted: “Many people would like to see [@Nigel_Farage] represent Great Britain as their Ambassador to the United States. He would do a great job!”
It led to the British government immediately shooting down the suggestion, saying: “There is no vacancy. We already have an excellent ambassador to the US.”
Peter Westmacott, Mr Darroch’s predecessor as ambassador to the US, has suggested the leak may have been intended to pressure the next prime minister to choose “someone already regarded as a ‘friend’ by the Trump administration” and “less ready to speak truth to power”.
During his state visit Mr Trump said Brexit “should happen” and tweeted in June: “Big trade deal is ready once UK gets rid of it shackles. Already starting to talk.”
Whilst in the EU it is not possible for the UK to conduct trade negotiations as members can only do it jointly as a bloc.
But a no-deal Brexit would see this become a reality.
The front runner in the UK candidacy to become the next UK prime minister, Boris Johnson, is a champion of a no-deal Brexit.
In a heated televised debate with his rival on Tuesday Mr Johnson – who has been backed by Mr Trump - refused to support Mr Darroch, unlike his rival Foreign Secretary Jeremy Hunt who said under his leadership Mr Darroch “would stay”.
Mr Johnson was accused of throwing Mr Darroch under a bus on Thursday as less than 24 hours later it prompted the envoy to tender his resignation.
The UK's opposition foreign secretary Emily Thornberry accused Mr Trump of "bullying" him out of his job.
"The fact that Sir Kim has been bullied out of his job, because of Donald Trump's tantrums and Boris Johnson's pathetic lick-spittle response, is something that shames our country," she said on Thursday.
US diplomat Lewis Lukens said the resignation was "unprecedented".
"I didn't expect it to happen so quickly. The UK government will have to pick a new one fairly quickly and have to make a decision on what kind of person is sent there to rebuild bridges with President Trump. It is a tough call for the British government - send someone who he will like or a more seasoned person who will have a better sense of how to navigate these tricky political waters."
Robin Niblett, director of Chatem House, had warned that removal of Mr Darroch by the new UK leader could lead to the new prime minister being seen as “a poodle” and had pre-empted that the envoy would “pay the price”.
“As long as there will be a new prime minister and a new ambassador to the US between now and the end of the year this will ebb away,” he said.
“The UK remains a key partner on a whole range of issues. This is Donald Trump’s angry tweets and Mr Darroch will pay the price.
“For the next prime minister the relation with US is the most central bilateral association, and how he manages it will be defined in the first few days of the job. It will put Britain in a poodle capacity if he dismisses him in few days of job. The US relationship is critical to the job.”
Mr Johnson had earlier stated that the special relationship will stand.
“The US has been and will be our political and military friend,” he said.
Former UK foreign minister Alistair Burt has said that despite the recent events the special relationship will "carry on".
“I doubt UK influence is affected in anyway. I think we just carry on.
“I don’t think anything in the analyse was anything we have not heard before. It was an entirely predictable reaction and we shouldn’t rise to it.”
But Tom Fletcher, a former British ambassador to Lebanon, has warned it will be a “hard period ahead” and says the next prime minister will now have to decide on how he will handle that relationship with the White House going forward - “whether to push back or have a more behind-the-scenes role”.
In the meantime, a “robust” hunt for the mole behind the leak continues.