Tony Blair's team in 10 Downing St redefined the role of the British ambassador to Washington on dispatching its envoy to the administration of Bill Clinton.
Sir Christopher Meyer was instructed to enter the deepest crevices of the White House and stay there. It was advice that found its apotheosis when Mr Blair later visited George W Bush's ranch in Texas – accompanied by Mr Meyer – and found common bond with the US president over their shared use of Colgate toothpaste.
Much has been made of the privileged position that the British ambassador enjoys in Washington with much greater access to the West Wing than other envoys. The enviable embassy operation regularly hosts the most powerful faces in the US capital.
Sir Kim Darroch's resignation on Wednesday is not just the nadir of his own career but an unprecedented low point for British influence with the country's closest ally.
The head of the British diplomatic service, Sir Simon McDonald, paid tribute to his departing colleague, noting he had been targeted by a malicious leak for simply doing his job. Another retired mandarin said he had been taken out by an act of political sabotage.
Many hands bear the blood of the envoy: the leaker, Donald Trump and Boris Johnson, the ex-foreign secretary bidding to be prime minister who damned Mr Darroch with equivocal support in a leadership debate the night before.
As Mr Blair's maxim from more than 20 years before illustrates, there is also an iron law at work. Britain with its distinct strategic interests in the Anglosphere cannot allow anything to damage its main alliance.
The idea that Mr Darroch could take a summer break and spend the autumn packing for London before retirement at the end of the year was a non-starter. Mr Trump, the most powerful man in the world, had decided he would not deal with him.
The enduring principle that countries choose their own ambassador and do not have the envoy foisted on them was not a real world option.
Some in London talked, as the showdown unfolded, of a Love Actually moment. This is the 2003 film in which Hugh Grant, the Blair-styled prime minister, confronts the boorish US president. Speaking on behalf of the country of Shakespeare and The Beatles, Mr Grant tells the American: "A friend who bullies us is no longer a friend."
Mr Trump conversely knows that Britain is uniquely vulnerable. It has turned to the protectionist US president to seek a trade deal to offset some of the losses it will incur when it leaves the European Union.
The likely ascent of Mr Johnson means London will scramble pell mell for more access to American markets, even though the terms imposed by the White House are likely to erode Britain's multi-billion dollar annual trade surplus with the US.
British diplomats have for decades sought to safeguard the Special Relationship between the US and UK in the military, security and diplomatic spheres. Moving away from common European policies means London needs more than ever a close functioning alliance with Washington.
The showdown over the ambassador has not been allowed get in the way of that tie-up. Just this week London is thought to have agreed to join France in adding scores of troops to its special forces deployment in Syria to ease the US draw down.
It is likely that Britain would be at the forefront of countries backing the US initiative to establish an international naval coalition in the Arabian Gulf.
These issues illustrate just why the US relationship matters so much to Britain. It also affects London's ties and standing with other countries around the world, such as the countries of the Gulf.
Unlike the American diplomatic service, the presence of political appointees in the ranks of British ambassadors is a rarity.
There is only one appointee currently, Edward Llewellyn, who was David Cameron's chief of staff and is now ambassador to Paris. Mr Llewellyn is a Francophile with attendant language skills who is married to a French national. There has been no serious murmurings against his tenure.
One of the speculations around the Darroch leak is that it was done to engineer an opportunity to place a Brexit-supporting, Trump-friendly ambassador in Washington.
Mr Johnson himself said the appointment was a "politically-sensitive" one that he alone would make as prime minister.
Finding a Johnson soulmate who is up the job will not be as easy as might be assumed.