Meanwhile, Danny Kruger, a ministerial aide in Michael Gove’s Levelling Up department, and Miriam Cates, another member of the 2019 intake of MPs, write in The Telegraph that the Conservatives “need a new way forward”. They warn that the party must “remember what makes us Conservatives”, including “sound money and low taxes”.

On Friday night, Sir Iain Duncan Smith, the former Conservative leader warned that ensuring that Downing Street became “structured and disciplined” would be “the key litmus test” for disaffected MPs.

A second backbencher told The Telegraph that they had passed a letter of no confidence in Mr Johnson to Sir Graham Brady, the chairman of the 1922 committee of MPs, after Sir Roger Gale, a veteran backbencher, said that he had submitted a letter earlier this year. “We have to be ruthless. The alternative is a Labour government,” the MP said. Caroline Nokes, a minister under Mrs May, was said to have told colleagues that Mr Johnson should go. She declined to comment this weekend.

Ms da Costa, who left Downing Street in August, said of No 10: “The whole system doesn’t work. It is cultural. Dan doesn’t believe in fostering a team – instead everyone is kept in their lane – and he doesn’t like challenge.