Tempers were raised during a phone call that reportedly took place between the prime minister and Iain Duncan Smith before the pro-Brexit MP resigned as work and pensions secretary. Anticipating the mayhem his decision to quit would unleash, David Cameron is said to have pleaded with Duncan Smith to stay on. But fearing it was a play for time so he could be briefed against, Duncan Smith refused and the prime minister reportedly "threw his toys out of the pram" in an expletive-laden rant.

"You s**t," he told his long-time colleague, according to The Mail on Sunday newspaper. "You're dishonourable."

Shortly after the call, Duncan Smith, once dubbed "the quiet man" before his ousting as Conservative Party leader in 2003, released his scathing resignation letter in which he said that planned cuts to disability benefits in George Osborne's budget were "not defensible".

It included plans to alter Personal Independence Payments (PIP), which will replace Disability Living Allowance (DLA) in January 2017, to cut £4.4bn from the government's benefits bill.

IDS: defender of the disabled?

Calling the changes "a compromise too far", Duncan Smith said they were "defensible in narrow terms, given the continuing deficit" but "they are not defensible in the way that they were placed in a budget that benefits higher earning taxpayers".

Duncan Smith's announcement after six years in his job, came hours after government sources signalled that they were going to place cuts on disability benefits on hold in the face of a rebellion by Tory backbenchers, many of whom wrote to Osborne saying measures would cost the Conservative Party the next election.

Cameron said he was "puzzled and disappointed" by his decision to quit, adding that Duncan Smith as part of the Cabinet, had "collectively agreed" to the budget.

Defence Secretary Michael Fallon confirmed this, saying: "The entire Cabinet endorsed the Budget, including Iain Duncan Smith."

Brexit plot

Others, including Baroness Ros Altmann accused Duncan Smith, her former boss, of trying to further his campaign for Britain to leave the European Union (EU).

"This really seems to be about the European referendum campaign," she said in a statement. "He seems to want to do maximum damage to the party leadership in order to further his campaign to try to get Britain to leave the EU.

She added: "As far as I could tell, he appeared to spend much of the last few months plotting over Europe and against the leadership of the party and it seemed to me he had been planning to find a reason to resign for a long time."

Duncan Smith was quickly replaced by Stephen Crabb, who has served as the MP for Preseli Pembrokeshire since 2005 and worked as the secretary of state for Wales for the last two years. He previously worked as a government whip.

Shortly after taking up his new role Crabb confirmed that the cuts will "not be going ahead".

"We're not going to be going ahead with these cuts to disability benefits that were proposed on budget day," he told Radio Pembrokeshire, adding that the subject was discussed before he took up the position.