The former chairman of the 1922 Committee has revealed the backroom tensions and deals behind the most turbulent decade in Conservative Party history for the first time.

Graham Brady has detailed his private conversations with prime ministers as they were forced out of power and lifted the lid on his role as Brexit, the pandemic and leadership turmoil culminated in electoral disaster for the Tories.

In his autobiography, Kingmaker, serialised in The Telegraph, Lord Brady reveals that Rishi Sunak was not forced to call an early election, because only 10 letters of no confidence in him had been submitted.

In further revelations, he says Penny Mordaunt suggested earlier in the year that she could replace Mr Sunak and that, on the day the former prime minister announced that the country would go to the polls, Andrea Leadsom tried to stop him.

According to Lord Brady, Boris Johnson became so fed up with backbenchers criticising his adviser Dominic Cummings during the pandemic that he called them “spineless chicken s—”.

In his autobiography, Kingmaker, serialised in The Telegraph, Lord Brady reveals that Rishi Sunak was not forced to call an early election

Although Lord Brady insists the Tory party is not “ungovernable”, his book exposes several attempts to oust sitting prime ministers – including Jeremy Hunt, Sajid Javid and Michael Gove moving against the “wooden” Theresa May at the height of the Brexit saga.

Mr Hunt is also alleged to have told Lord Brady that Liz Truss had to quit as prime minister immediately, shortly after being appointed as her Chancellor.

Lord Brady also claims that David Cameron and George Osborne had contempt for people who did not share their backgrounds.

The 57-year-old oversaw the departures of five Conservative prime ministers during his tumultuous 14-year tenure as chairman of the 1922 Committee from 2010. As chairman, it was his job to tell prime ministers when they had lost the confidence of their MPs.

The powerful group of backbenchers runs the selection process for new Tory leaders. The chairman collects, entirely in private, letters of no confidence if MPs want to oust a leader.

It is the first time a former chairman has revealed the secrets of their time in charge.

It had been suggested that Mr Sunak was left with no choice but to call an election because he was about to face a vote of no confidence. Reports claimed Lord Brady had received “around 50” letters – almost at the threshold of 53 required.

However, Lord Brady writes: “A rumour spread that Rishi had called the election because I had told him that he was about to face a confidence vote. I had given no such indication. As we headed off towards the smoke of battle, there were 10 letters sitting in my safe.”

The knives were out for Mr Sunak before the local elections in May, when Lord Brady claims Ms Mordaunt launched an early bid to replace him.

Revealing that a rumour had started that “Rishi would just walk away” if the results were poor, he writes: “During a meeting with me soon after, the Leader of the Commons Penny Mordaunt said: ‘I wouldn’t ask you… but if anything did happen.. if Rishi walked away after the local elections, I hope there is a plan for a calm transition?’”

Mr Sunak called Lord Brady personally on May 22 to tell him he would be announcing the July 4 election that afternoon – to the shock and horror of Conservative colleagues, who convened an emergency meeting of the 1922 Committee.

Dame Andrea Leadsom, then a health minister, apparently asked Lord Brady: “If enough of us submit letters to you calling for a vote of no confidence, can we stop the prime minister from leading the Conservative Party to its destruction?”

Like many Tories, Lord Brady – who was a vocal member of the lockdown-sceptic Covid Recovery Group of Conservative MPs –repeatedly clashed with Boris Johnson over his “draconian” approach to the pandemic.

Sir Graham Brady announces that Boris Johnson has survived an attempt by Tory MPs to oust him as party leader in June 2022

Mr Johnson apparently became so irritated by Tories criticising Mr Cummings over his lockdown-breaking Barnard Castle trip in 2020 that he angrily dubbed them “spineless chicken s—”, despite saying that Mr Cummings was “not sane”.

Echoing Mr Cummings’ description of his former boss as a “shopping trolley” during the pandemic, Lord Brady claims Mr Johnson railed against the “stupid f—ing two-metre rule” and “f—ing scientists” while also telling those who questioned his Covid measures: “How many people would you let die?”

He also refused to step down right up to the night before his resignation in 2022, telling Lord Brady: “They would be mad to get rid of a leader who won the biggest Conservative majority since 1987.”

Such was the skulduggery that after Ms Truss blamed Kwasi Kwarteng for the disastrous mini-Budget in 2022 and replaced him with Mr Hunt, the new chancellor then told Lord Brady that she “must go”.

Ms Truss resigned six days later after a brief conversation with Lord Brady, who was then forced to “hide” inside No 10 until she made her statement to avoid the press pack gathered outside.

Lord Brady, the former MP for Altrincham and Sale who resigned from Lord Cameron’s shadow Cabinet in 2007 over his opposition to grammar schools, accuses the former prime minister of an “act of petulance” in resigning the day after the EU referendum in 2016.

He argues that the behaviour of Lord Cameron and Mr Osborne, his chancellor, was “unprincipled, both in the run-up to the campaign, and during it…”.

During a series of scandals in 2014, he reveals that the Old Etonian once told him: “The fact is, a lot of politics is just s—: it’s choosing the least bad option… Life would be easier if colleagues paid their expenses on time [sic] and didn’t snort coke and sodomise each other.”