Dominic Cummings has claimed the Prime Minister considered calling off a high-profile leak inquiry when it emerged the source of the leak may have been his fiancee's best friend.

Mr Johnson's former top adviser issued a statement following claims overnight that he was behind a series of sensitive government leaks including one about future lockdown policy. 

An inquiry was launched into the leak, which detailed plans for a further lockdown, prior to the PM making the announcement.

In a bombshell accusation, Mr Cummings said Boris Johnson considered calling off the leak inquiry after it was suggested that the Henry Newman, the "best friend" of his fiancee Carrie Symonds, was behind it.

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He explained: "Last year there was a meeting between the PM, Cabinet Secretary, the Director of Communications and me regarding the leak of the decision for a further lockdown on the Friday evening immediately after the meeting in the Cabinet Room that made the decision.

"The Cabinet Secretary told the PM that the leak was neither me nor the then-Director of Communications [Lee Caine] and that ‘all the evidence definitely leads to Henry Newman and others in that office, I’m just trying to get the communications data to prove it’.

"The PM was very upset about this. He said to me afterwards, ‘If Newman is confirmed as the leaker then I will have to fire him, and this will cause me very serious problems with Carrie as they’re best friends … [pause] perhaps we could get the Cabinet Secretary to stop the leak inquiry?'

"I told him that this was ‘mad’ and totally unethical, that he had ordered the inquiry himself and authorised the Cabinet Secretary to use more invasive methods than are usually applied to leak inquiries because of the seriousness of the leak." 

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Mr Cummings said that a statement was authorised declaring that the inquiriy had "shown that neither I nor the then-Director of Communications were the ‘lockdown leakers’"

He added that the Prime Minister had described previous rumours suggesting Mr Cummings, or the former Director of Communications Lee Caine, were behind the leak as "total b******t" adding: "The PM therefore knows that I was not the source of the leak and that the Cabinet Secretary authorised the Prime Minister’s Official Spokesman to tell the media this, yet he has now authorised his Director of Communications to make this accusation."