But now - finally - Nadine Dorries is giving up the tiresome chore of being an MP to become a full-time chat-show host, novelist, newspaper columnist and celebrity.

And she's not going quietly. Her brutal hit-job on Rishi Sunak in her resignation letter doesn't pull any punches. But after the damage her conduct in the past few months has already inflicted on the Tory Party she'll win little sympathy from Tory MPs.

Despite briefly serving in cabinet in the relatively junior position of culture secretary under her not-so-secret crush Boris Johnson, she's hardly one of the big beasts of the party or a substantial political figure whose resignation will send shock waves through her party.

While she's making a lot of noise and clearly hell-bent on taking her revenge on Mr Sunak for his role in the demise of her beloved Boris, we're not talking political earthquake here like the resignation of cabinet titans like Michael Heseltine from Margaret Thatcher's cabinet in 1986 or Robin Cook over Sir Tony Blair's Iraq war in 2003.

For most of her political career, Nadine Dorries has been a maverick backbencher whose main claim to fame was appearing on I'm A Celebrity, Get Me Out Of Here in 2012 without permission, for which she had the Conservative whip withdrawn.

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The only Tory leader to whom she was totally devoted was Boris Johnson. She sobbed in the news conference when he bottled it in 2016 and announced he would not stand in the leadership contest after David Cameron quit following his Brexit referendum humiliation.

She never had any time for Mr Cameron. In 2012 she denounced the then PM and chancellor George Osborne as "two arrogant posh boys who don't know the price of milk".

In her resignation letter attacking Mr Sunak she refers to her time in politics before she became MP for Mid Bedfordshire in 2005. She was a special adviser to the unworldly Oliver Letwin. Talk about the odd couple: the working-class ex-nurse from Liverpool and the old Etonian toff.

Former Fleet Street executive and Tory spin doctor Henry Macrory tells an amusing story about Ms Dorries' time working for Letwin when he was shadow chancellor.

Discovering her frantically applying make-up to his face, Mr Macrory asked what she was doing. "Oliver's doing an interview," she replied. "For whom?" Macrory enquired. "Moneybox!" she said proudly. "But Moneybox is a radio programme," he informed her.

Threatened to 'kick Sky News journalist's balls'

She could be fiery too, when criticised. Some years back she telephoned a Sky News journalist on a Saturday morning and announced that after a Sky colleague had been critical of her: "You can tell him, I'm going to kick his balls!"

She has never been more fiery than in her resignation letter. She continues to insist that, despite criticism from colleagues, she has "continued to work for my constituents faithfully and diligently to this day".

Really? She hasn't spoken in the Commons for more than a year and has only voted six times this year. Constituents claim they haven't seen her "in years".

Directing a "posh boy" attack on Mr Sunak, she claims that as chancellor "you flashed your gleaming smile in your Prada shoes and Savile Row suit" delivered "platitudes" and spoke "illustrating how wonderful life was in California".

Turning to "the political assassination of Boris Johnson", she claims there's a "dark story" which she intends to tell in a book "which exposes how the democratic process at the heart of our party has been corrupted".

Credible? Her critics will no doubt accuse her of peddling wild conspiracy theories.

Her claim that Mr Sunak is guilty of "demeaning his office by opening the gates to whip up a public frenzy against one of his own MPs" appears grossly over the top. Most Tory MPs, by now, are sympathetic to the frustration felt by the prime minister about her behaviour.

However, to be fair to her, there will be sympathy for her over her disclosure that police have had to visit her home because of threats in recent weeks.

Zombie parliament claims are pretty spot on

And her description of a "zombie parliament where nothing meaningful has happened" and "the government is adrift" is pretty spot on.

How many times has the Commons business collapsed in mid-afternoon in recent months and big votes dodged? Plenty. Few will dispute that claim by Ms Dorries.

She has a point, too about Boris Johnson's 2019 manifesto being "completely abandoned".

The claim that 200 or more Tory MPs face an "electoral tsunami", however, rather contradicts her claim that "there's no affection for Keir Starmer".

Nadine Dorries has her fans and supporters. They'll claim that from her working-class background she's achieved great successes inside and outside politics: her novels are massively successful, for instance, and have earned her a lot of money.

But politics is tribal and apart from the brief period when Boris Johnson made her a minister and then promoted her to the cabinet she's mostly been an outsider.

And the Tory party is ruthlessly unforgiving. Labour will lap up her attacks on Mr Sunak. The leaflets and attack ads quoting her are no doubt being prepared already.

Her behaviour of the past few months has almost certainly cost the Tories another safe seat in the by-election that she now says she's ready to trigger. And her book on Mr Johnson is timed to cause Mr Sunak and the party high command maximum damage at the Conservative Party conference.

Nadine Dorries is certainly mad. But mad meaning angry, furious and incandescent, rather than in the way Labour MPs portray her. And her prolific career outside parliament proves she's no dosser.

But many Tory MPs will conclude, after reading her valedictory diatribe, that in missing out on the peerage that Boris Johnson promised her and she so obviously craves, she's only got herself to blame.