The waters of the Atlantic are choppier still. The United Kingdom’s equation with the United States of America has plunged beyond measure with Wednesday’s resignation of Sir Kim Darroch as Her Majesty’s ambassador to Washington ~ a dramatic departure from the bonhomie that had marked the Anglo-US invasion of Iraq in 2003.

The rupture comes about at a critical juncture for Britain, specifically when Brexit has rendered governance in limbo. Sir Kim was the target of a hostile act, going by the certitudes of diplomacy ~ the leaking of confidential reports that had criticised President Trump’s administration.

The observations described a dysfunctional presidency, and by the benchmark of objectivity, the UK’s man in the US was right. The ambassador may have done nothing wrong in passing that information back to London; but the breach of confidentiality was embarrassing. Reports do suggest that he has resigned on his own volition.

Markedly, Downing Street supported him and correctly so though predictably enough, President Trump has condemned the development on Twitter. Within the establishment, such as it now exists, Boris Johnson, the Prime Minister in waiting, has not supported Sir Kim, and this is said to be a sinister indication of his priorities.

Even before stepping into No.10, as generally expected, he has developed a remarkable degree of personal chemistry with President Trump. Sir Kim’s resignation stems from the fear that his ability to perform his duties had been fatally compromised. In his letter of resignation, he has attributed the “critical damage” not to the leak per se, but to the ensuing speculation about his future. It would have been a grave embarrasment for Britain if he had resigned at the behest of a foreign Head of State.

If Mr Johnson had offered unequivocal support, the situation would have been different. In the net, Sir Kim has opted for an honourable exit. Of course, a united political front in the UK would have been in a position to resist President Trump’s petulant outbursts, and thus contain the episode and its fallout. At this juncture, the damage to trans-Atlantic relations has been considerable.

It appears that Mr Johnson has accorded precedence to his cordial relations with Mr Trump rather than defend the ambassador. And this explains Sir Kim’s remarkably prescient conclusion that Downing Street, under Mr Johnson, “would not respect or protect officials ~ even the most senior envoys of Her Majesty’s government ~ if it was expedient to see them traduced”.

Relations between the two countries have seldom been so complex, not the least because the likes of Donald Trump and Boris Johnson are the prominent characters in the dramatis personnae. The latter’s stint as Foreign Secretary wasn’t particularly notable. He has mishandled the latest red herring in the diplomatic trail. Hence the cynical observation in London that he has managed to diminish the office of Prime Minister before even reaching it. Loyalty (to the Crown) can be freakish when not suspicious.