Unencumbered by such base hindrances as loyalty or the need to get another job, Cummings, who has family wealth to fall back on, is prepared to do what it takes to bring down Johnson, no matter the cost to his own reputation.

On Tuesday, it was reported that Sue Gray, the senior civil servant investigating “partygate”, will interview Cummings over his claim that the PM was warned the May 20 event would break lockdown rules. Johnson has denied this outright, and neither Gray nor anyone else is likely to place more weight on Cummings’s word than that of the PM. But what if Cummings has held back a piece of evidence to set a trap for his prey?

Cummings has said there are “many other photos of parties after I left yet to appear”. Rumours are swirling around Westminster of a video of Johnson at the May 20 event. If it exists, Cummings or an ally might be waiting for Gray to exonerate the Prime Minister – and for him to address the Commons – before releasing evidence that might show he has misled Parliament. Downing Street made it clear yesterday that Johnson would quit if he was found to have misled Parliament, saying that “the ministerial code is very clear on this point” and that the Prime Minister “abides by that”. It suggests the PM and his aides are supremely confident that Gray will not conclude that Johnson lied to Parliament, and that Cummings does not have evidence to the contrary, nor will there be any substance to his claim that other witnesses will “swear under oath” that the PM lied.

Cummings does have a track record when it comes to boasting of corroborating evidence. When he told MPs about the “bodies pile high” comment, he suggested others would back his version of events – but no one did so on the record. He claimed to have evidence that Matt Hancock lied repeatedly about Covid policy when he was health secretary, but failed to produce it after his marathon appearance before a select committee.

Similarly, Cummings suggested he and others inside No 10 were plotting to oust Johnson the month after his landslide general election win of 2019 – but no one has backed up his story.

Could it be that Cummings has overestimated the support he has from those he regards as allies? Or does he simply enjoy tormenting the man who had the temerity to tell him he was no longer needed?

“He is just a fantasist,” said one Tory backbencher. “A lot of people are starting to see this as a witch hunt, and that’s partly because it is all originating from Cummings.”

Meanwhile, Cummings has directly addressed Tory MPs on Twitter, telling them that they must choose a new leader and will harm their chances of re-election if they “delay the inevitable”, adding: “Tick tock…” Yet, as the MP pointed out, Cummings showed nothing but contempt for Tory backbenchers during his time in Downing Street, refusing to speak to most of them and delighting in telling them: “I don’t know who you are.”