Who would be an ethics adviser to this government? Unless there is a figure lurking in the wings, it is unclear who would be prepared to fill one of the most tainted jobs in public life.

It is always possible that No 10 has an immediate replacement in mind. But Boris Johnson found it hard enough to recruit this one – it took five months for him to appoint Lord Geidt, after the bitter circumstances around the resignation of the preceding ethics adviser, Sir Alex Allan, in November 2020.

Allan told Johnson that his home secretary, Priti Patel, had broken the ministerial code on bullying. The prime minister then refused to sack her, making Allan’s position untenable.

Finding anyone willing to advise Johnson on ethics when he had already shown himself willing to comprehensively overrule their advice was always going to prove tricky.

Even at the 11th hour during the run up to Geidt’s appointment, it was rumoured that the long-serving palace aide had cold feet after the publication of allegations by Dominic Cummings that the prime minister had broken the law.

When he was appointed, those who had previously worked with Geidt said he would not be Johnson’s patsy. But there were several instances where his conclusions pulled the prime minister out of the mire.

Immediately tasked with investigating the donations towards the refurbishment of the prime minister’s flat – dubbed “Wallpapergate” by some in the press – Geidt cleared Johnson of any wrongdoing, though he was just critical enough in the report to avoid allegations of a full whitewash.

Yet he became a favoured target of Cummings in his blog posts, accused of deliberately not seeking out key witnesses for interview over what he alleged were “illegal donations”.

Geidt came under renewed scrutiny when he suggested in a letter to Johnson that he might have broken the ministerial code – which Johnson then cleared himself of doing in his reply to Geidt.

In an increasingly uncomfortable evidence session in front of MPs, Geidt appeared to struggle in real-time with his oxymoronic role as a guardian of the prime minister’s ethical code who is subject to the whim of the prime minister. At one stage, he tellingly described himself as an “asset of the prime minister” and admitted it was difficult to rid himself of the impression that it was a “cosy” relationship.

Members of the committee put it as politely as they could that Geidt was putting himself in an untenable position. “It will have been very difficult for him to read stories about how he was a patsy, that is absolutely not how he views himself at all,” one senior Whitehall source said.

If there is no immediate replacement, senior Whitehall sources now suspect Johnson may dispense with the role altogether, given the difficulty of recruiting a successor. Johnson has already rewritten the ministerial code to limit the impact of its enforcement.

It now makes clear that ministers will not always be expected to resign for breaching the code of conduct – they could apologise or temporarily lose their pay instead.

The changes also meant Geidt did not gain the power to launch his own investigations, though he told MPs that he would expect to be granted an investigation if he requested one. Johnson rewrote the foreword to the ministerial code, removing all references to honesty, integrity, transparency and accountability.

There is likely to be a very limited pool of candidates who would be prepared to put their reputation on the line for a prime minister who has made clear how little store he sets by the code they must preserve.