Sometimes leaks from within the government are striking not just for their content, but also for the motive behind them.

The content of telegrams sent from Washington by Kim Darroch, Britain’s ambassador to the US, and disclosed by the Mail on Sunday, is a case in point. The leak is also striking for what it tells us about the struggle for influence at the top of a Boris Johnson-led Conservative party.

The telegrams provide both a Michael Wolff-style assessment of the chaos inside the early years of Trump’s presidency and an unflattering – if not damaging – account of Trump’s own personality defects.

They also give some insights into how Britain seeks to maintain its influence in the White House by trying to “flood the zone” of opinion formers or outer circles of Trump’s advisers. Recent episodes such as the Trump team’s glowing assessment of the president’s state visit, and his tête à tête with the Queen, also get a mention.

Darroch appears dismissive of the president’s strategy towards Iran. While the material is potentially the most diplomatically sensitive, it is hardly surprising that the UK and the US do not agree on whether efforts should be made to preserve the Iran nuclear deal.

The issue over the past year has largely been how to contain that divergence of opinion so it does not expose other aspects of the special relationship. Trump however will be angry that Darroch does not believe the president pulled back from attacking Iran for fear of civilian casualties, an assessment that insinuates the president was lying.

Any leak inquiry will be working to cross check how such a wide array of leaks covering such a long time period came to be in the possession of someone with the motive of putting them in the public domain.

Much will depend on how the president, and the most likely new British prime minister react. The danger is that Trump will tweet something dismissive, but then harbour a deep grudge against Britain’s professional diplomatic service. Some might tell him the Whitehall machine is a nest of snobbish anti-populist opponents of Brexit.

The real challenge though is actually facing the likely next prime minister, Boris Johnson, who prides himself on his proximity to the Trump family, including Jared Kushner, despite their quite different personalities.

One of the first decisions on the in tray for a Johnson premiership will be a replacement for Kim Darroch, who is due to depart at the end of the year anyway.

There have been reports that Mark Sedwill, the current cabinet secretary, is being lined up for the position. The US administration – which sees ambassadorships as rewards for political friends and donors – may be suspicious of Sedwill, and would prefer a true Brexiter to guide the special relationship as Britain detaches itself from Europe, and seeks a free trade deal with the US.

Sedwill, a widely admired career civil servant with good links to the US intelligence services, may not fit that bill, but Nigel Farage – who pretty openly campaigned for the job before Darroch’s appointment in 2016 – does.

Farage will certainly benefit from the leak and what is notable is that he is one of the voices in the Mail piece calling for Darroch’s immediate resignation.

The journalist responsible for the scoop, Isabel Oakeshott, is close to Nigel Farage’s Brexit party. She has even been previously accused of withholding newsworthy information that might have damaged her best Brexit contacts, a charge she denies. Her cooperation with former Conservative chairman Michael Ashcroft, indicates she operates in the twilight world between journalism and political activism.

But despite Oakeshott and Farage’s perception of the latter being a suitable Washington envoy, they did need someone to supply them with the ammunition in the form of the leaks.

There are politicians that have fallen out with Sedwill that are now close to Johnson, such as Gavin Williamson, the former defence secretary. Williamson remains bitter at how Sedwill oversaw an official inquiry into a leak of a national security committee meeting on Huawei that found its way into the Daily Telegraph within hours of the meeting ending. He insists he had nothing to do with the leak, and feels aggrieved that he lost his job largely on the recommendation of the Sedwill’s findings, calling the inquiry a “kangaroo court”.

But Sedwill’s inquiry was in April and Williamson was asked to leave the government in May so he would not have access to these papers covering a state visit in June. His hands look clean.

Moreover, a quick phone chat with friendly journalists about a cabinet meeting is also of a different order to wholesale leaking of Darroch’s telegrams. Ironically the man most likely to lead the inevitable leak inquiry is, of course, Mark Sedwill.