The generational change was symbolised by the retirement of Ken Clarke, whose cabinet career spanned 25 years. He left the front bench vowing to continue to fight from the backbenches to keep Britain in the EU.
While Mr Clarke was toasting his retirement with a glass of red wine and a curry at the Kennington Tandoori, Mr Cameron was delivering the bad news to a series of ministers from his office behind the Speaker's chair.
David Jones, Welsh secretary, was the first to confirm he was being removed from the cabinet while Alan Duncan, the international development secretary, said he was leaving the front bench voluntarily.
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David Willetts, the science minister who was at the heart of talks with Pfizer in its aborted takeover bid for AstraZeneca, also lost his job and announced he would step down as an MP next year.
Two ministers pursuing policies that were once at the heart of Mr Cameron's modernising drive also left the government: Nick Hurd, the "Big Society" minister, and Greg Barker, climate change minister.
Damian Green, the police minister whose office was raided by police when the Tories were in opposition, was another minister to lose his job.
Owen Paterson, environment secretary, Andrew Lansley, Leader of the House, and Bob Kerslake, head of the civil service, were also among cabinet ministers sacked last night.
Mr Cameron's decision to conduct the cull in the House of Commons spared ministers the indignity of having to walk down Downing St past the cameras to learn their fate.
By contrast, those winning promotion will walk to Number 10 to illustrate what Mr Cameron will claim is a more diverse ministerial team.
They are expected to include Nicky Morgan, Treasury minister, Esther McVey, employment minister, and Liz Truss, education minister, while other MPs elected only four years ago will be given a chance to prove themselves in government.
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Mr Clarke told the Financial Times he had decided to retire before people started to wonder how to get rid of him and before he made "a pig's ear of something". He plans to write an autobiography.
—By George Parker, Elizabeth Rigby and Jim Pickard