It helps explain why Sunak loyalists have pointed the finger at Number 10 when it comes to identifying a culprit for the leaks of the Chancellor’s personal affairs.

Mr Sunak has placed a high-stakes bet by ordering a leak inquiry: if it identifies a senior member of Mr Johnson’s staff as the leaker, he may feel emboldened to mount a leadership challenge, but it could also blow up in his face if, for instance, it turned out that one of his own staff was stabbing him in the back.

His decision to ask Lord Geidt, the Prime Minister’s independent adviser on standards, to review his personal arrangements is another gamble. Mr Sunak insists that he followed the advice of his permanent secretaries at all times on what he should and should not publicly declare, but Lord Geidt could rule that Mr Sunak should have been more transparent, which would leave the Chancellor in a difficult position.

Mr Sunak is understood to have gone through his and his wife’s finances when he first became a minister in 2018 with Helen MacNamara, the head of propriety and ethics, including their green cards and his wife’s non-dom status, and was given the all-clear.

Many Tory backbenchers believe Mr Sunak could be embarrassed if he did try to run for leader.

One said: “Everything that has happened in the past week shows his lack of political awareness.

“I find it genuinely astonishing that he would have kept a green card and that they thought they could get away with his wife avoiding UK taxes.

“It may have all been within the rules, but it casts a big shadow over any suggestion that he has got the political wherewithal to hold the highest office. It also shows that if he was serious about becoming prime minister he should have had a better team around him.”

Some backbenchers and ministers, particularly those who have been through the misery of life on the opposition benches, believe Mr Sunak was promoted too quickly: having been an MP for less than seven years, he is the most inexperienced chancellor in living memory.

Ministerial advisers who have locked horns with the Chancellor’s team have taken delight in his difficulties, describing him and his wife as “Rishi Notax and Akshata Murky” and swapping laughter emojis on WhatsApp groups.