Dominic Cummings has claimed that he held talks about trying to force Boris Johnson out of 10 Downing Street just weeks after the Conservatives’ last general election landslide.
The Prime Minister’s former chief adviser claimed he held discussions about trying to replace Mr Johnson over his apparent unsuitability to run the country during a BBC interview.
Mr Cummings said advisers around the PM had raised the prospect of a coup against Mr Johnson because the Prime Minister’s now-wife Carrie Johnson was trying to force them out.
He said: "Before even mid-January  we were having meetings in Number 10 saying it’s clear that Carrie wants rid of all of us…
"At that point we were already saying by the summer either we’ll all have gone from here or we’ll be in the process of trying to get rid of him and get someone else in as Prime Minister.”
Mr Cummings continued that Mrs Johnson’s view "was and is the Prime Minister doesn’t have a plan and he doesn’t know how Whitehall works".
He said: "In 2019 her view was better that it’s Dominic and the Vote Leave team than the civil service because that’s the route to winning and staying in Number 10.
"As soon as the election was won her view was ‘why should it be Dominic and the Vote Leave team?’ Why should it be me that’s pulling the strings?”
Mr Cummings claimed that his relationship with Mr Johnson was already breaking down “by summer 2020” in part because "it was driving him round the bend" that he was seen as "a kind of puppet for the Vote Leave team".
What Dominic Cummings told the BBC
Mr Cummings added that Mr Johnson "didn’t have an agenda. The Prime Minister’s only agenda is buy more trains, buy more buses, have more bikes and build the world’s most stupid tunnel to Ireland, that’s it”.
Mr Cummings said that he suspected Mrs Johnson of "interfering with appointments, people who she wanted to have fired, and she wanted to have people promoted in ways that I thought were unethical and unprofessional", which led to a big argument between the pair before he quit last November.
Turning to the 2016 European Union referendum, Mr Cummings, who was the brains behind the official Vote Leave campaign, said "anyone who says they’re sure about questions like that [Brexit] has got a screw loose, whether you’re on the Remain side or our side".
He added, "Questions like ‘is Brexit a good idea?’ No-one on earth knows the answer to that."
Speculating on his future, Mr Cummings suggested he could help to set up a new political party "to end the existing parties, to kill them off and create something different" based on the Vote Leave model.
He added: "You either have to take over one of those parties or create a new one that displaces them or create some other kind of entity which then ends up kind of assimilating or disrupting that power.”
Mr Cummings’s interview was given short-shrift by Tories loyal to Mr Johnson. Tory MP Conor Burns, who is close to Mr Johnson, said: "Dom is hellbent on revenge. He is operating to the law of diminishing returns, saying the same thing over and over again.
"I feel very sad about this. He made an enormous contribution to the Brexit campaign and the 2019 election but he is clearly determined to do the Prime Minister harm."
He added: "This is not revenge being a dish that is best served cold, this is revenge on loop. It is unedifying."
A Number 10 spokesman told the BBC: “Political appointments are entirely made by the Prime Minister.”
A spokesman for Mrs Johnson was approached for comment by The Telegraph.
On Tuesday night, a Government source suggested the interview had backfired on Mr Cummings. The source said it was a “Prince Andrew-level interview”.