Earlier in the day, Mr Raab was asked whether Mr Johnson should quit if he was fined and said: “Let’s wait and see … Allow the police to conduct their investigation and see, when they have ascertained the facts, quite what they conclude.”

The Prime Minister faced another difficult day on Tuesday as Peter Aldous became the 10th Conservative to demand his resignation and announce that he had submitted a letter of no confidence.

The MP for Waveney wrote on Twitter that he believed removing Mr Johnson from office was “in the best interests of the country, the Government and the Conservative Party”.

Andrew Mitchell, the former Cabinet minister who told Mr Johnson in the Commons this week that he no longer supported him, said Number 10 was being run like a “medieval court”.

Sir Charles Walker, the vetern Tory MP, also suggested Mr Johnson should consider stepping down.  

He told Channel 4 News it would show “great courage” if the Prime Minister were to say “I understand that I asked so much of the country and it needs to come to terms with that grief and pain and start the process of healing, and if it could do that better without me in Number 10 then I shall stand aside”.

Tom Hunt, the MP for Ipswich who was elected in 2019, said that “when the leader of our party makes a big mistake, I think it’s important to call this out”, but added that he was not convinced about the wisdom of sparking a party leadership contest at the moment.

Other Tory rebels warned that “if it takes a permanently organised circus” to keep Mr Johnson in power, his premiership “isn’t sustainable”.

But Jacob Rees-Mogg, the Commons Leader, said the “mood was positive” among Conservatives following Mr Johnson’s “upbeat” performance and promises of change at the 1922 committee on Monday night.