Ms Dorries was a stalwart ally of Boris Johnson, and has continuously criticised Mr Sunak since he took over as leader of the party and government last year.

She claims he - among many things - blocked her ascension to the House of Lords. This has been denied by Downing Street.

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Speaking to the Politics Hub with Sophy Ridge, Ms Dorries was asked why she had described Mr Sunak as "sickly nice" in her new book, The Plot.

Explaining what she meant, Ms Dorries said: "If you saw him in his interview with Elon Musk I think you know what I mean.

"There's a smile [that] is not always genuine - and I'm sure you've read many times yourself and heard many times yourself - but he was, he's quick to anger, and because that mask often slips."

Ms Dorries said she had seen this happening.

Asked when this occurred, she said it was "just an irritability" - adding that it was "very hard to put on an image, isn't it, all day".

"It's very hard to keep that fixed grin and that, you know, that cheerful chappy demeanour all day long when you're prime minister," she said.

"It's like 24 hours a day, so I'm not surprised the mask slips because it's quite hard to keep up that effort.

"I think that's part of the problem."

Asked about the recent reshuffle, Ms Dorries said she did not think it was right to sack Suella Braverman.

She accused Downing Street of lying about not signing off a controversial article authored by the former home secretary in which she accused the police of "playing favourites" with pro-Palestine protesters.

When Ms Dorries was a minister and Mr Johnson was in power, Downing Street came under scrutiny for its statements on partygate and Chris Pincher - the latter event precipitating the collapse of the administration.

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On Lord David Cameron's appointment as foreign secretary, Ms Dorries claimed the job was "created" so Lord Cameron could be put in the House of Lords - something she thinks would not have happened otherwise due to the Greensill lobbying scandal.

Sky News has contacted Number 10 and Lord Cameron for comment on Ms Dorries's claims.

Watch the interview tonight at 7pm on the Politics Hub with Sophy Ridge