Dominic Cummings has described how he struck a “deal” with Boris Johnson to become his senior adviser over a conversation in his living room.

Giving evidence to the Commons Science and Technology Committee, Mr Cummings said that as part of the arrangement he had insisted on his pet project, a new £800 million research funding agency based on the 1960s US Advanced Research Projects Agency (Arpa).

“The Prime Minister came to speak to me the Sunday before he became Prime Minister and said will I come to Downing Street to help sort out the huge Brexit nightmare,” he said.

“I said ‘Yes, if first of all you are deadly serious about actually getting Brexit done and avoiding a second referendum.

I figured I should be paid the same for trying to sort out the Brexit mess as I'd been paid for doing Vote Leave

“’Secondly, double the science budget, third create some Arpa-like entity and fourth support me in trying to change how Whitehall works because it’s a disaster zone’ and he said ‘deal.’”

Mr Cummings, who had worked with Mr Johnson on the EU Vote Leave campaign, was subsequently ousted from No 10 amid the fallout from an internal power struggle with the Prime Minister’s fiancee, Carrie Symonds.

He denied reports he had received a £45,000 pay rise following the pandemic, despite the controversy over his notorious trip to Barnard Castle in apparent breach of lockdown rules.

He told the committee that when he joined No 10 in the summer of 2019, he had actually insisted on a pay cut although he was later restored to the normal salary for his position.

“The media reports about me getting a pay rise after Covid are wrong.

“It is true that I interfered with the pay system regarding my own pay,” he said.

“When I arrived I was put on the normal pay band for my position of 140-something-thousand.

“I didn’t want that.

“I only wanted to be paid what I was paid in Vote Leave.

“I figured I should be paid the same for trying to sort out the Brexit mess as I’d been paid for doing Vote Leave.

“I asked for a pay cut which is what happened in summer 2019.

“When we are all rehired the day after the election then I moved back onto the normal pay grade for my position.”