Watch Iain Duncan Smith launch furious attack on 'deeply unfair' cuts by Cameron and Osborne

'I care for one thing and one thing only'

This is the moment Iain Duncan Smith launched a furious attack against the Prime Minister and the Chancellor over what he said were the “arbitrary” and “deeply unfair” benefit cuts that forced him to resign.

Known in Westminster as the “quiet man” of politics, the now-former Work and Pensions Secretary told the BBC’s Andrew Marr Show he had taken the “painful” decision not out of any personal ambition, but because the measures announced in last week’s Budget risked “damaging the Government, damaging the party, and actually damaging the country”.

In a extraordinary tirade, Mr Duncan Smith sought to dispel claims he had resigned as part of his campaign for Britain to leave the EU, or as a calculated bid to see either David Cameron or George Osborne pushed out.

But while he insisted “it’s not personal”, Mr Duncan Smith admitted he had been considering stepping down for more than a year over the way changes were being pushed through by the pair without “a greater collegiate sense to the way decisions are made”.

In his interview on Marr, the first since he announced his decision to resign on Friday, the former minister became increasingly passionate as he insisted that his only motivation for standing down was because he no longer had the power to push through social reforms.

He said: “I served in the Army because I care about my country and I care about the people who live here.

“I came into politics because I care about my country and I care about the people who live here.

“I do not have political ambition, I would not stand for leader and I would not support somebody who stands for leader at the moment. I am a supporter of the Prime Minister.

“I care for one thing and one thing only, and it is that the people who don’t get the choices that my children get are left behind.

“I do not want them left behind, I want them to be given that opportunity. And everything that I have tried to do has been about that.

“Yes, we can debate the things that people didn’t like because they are more about the deficit than about welfare reform.

“But, overarchingly, what I am passionate about is getting that work done so society is reformed, so that we have more of those people who have been left behind brought back into the sphere where we play daily but where they do not.

“That is what I have been about… It’s not easy, it’s painful to resign, I don’t want to have to resign, but I think it is the only way that we can do this.”