Iain Duncan Smith set for first post-resignation interview

British Prime Minister David Cameron was forced into a hasty cabinet reshuffle on Saturday as the dramatic resignation of a senior minister threatened to widen divisions over Europe within the ruling Conservative party.

"While they are defensible in narrow terms, given the continuing deficit, they are not defensible in the way they were placed within a Budget that benefits higher earning taxpayers".

"I think I can't do this any longer inside, I have to go out, resign and argue for this kind of process outside", he said.

She said she hoped Duncan Smith's replacement, Welsh Secretary Stephen Crabb, a member of the Conservative Christian Fellowship, will "not be afraid to do what is necessary to the inflated welfare budget".

A North disabled campaigner has welcomed the news of Iain Duncan Smith's resignation saying he had a "catastrophic impact" on the disabled.

The intervention, in an interview on the BBC's Andrew Marr show, came with Tory infighting threatening to spiral out of control.

Alun Cairns moved up the ranks in the Wales office to replace Crabb.

"I think the Cameron government will live to fight another day", Honeyman said.

"Having worked alongside him as a minister in the Department for Work and Pensions, I have seen that he championed the very package of reforms to disability benefits he now says is the reason he has resigned", she said.

He also confirmed he considered resigning a year ago after a series of spats with the Chancellor over cuts to tax credits and his flagship Universal Credit project, which is merging working age benefits and aims to ensure people are always better off in work.

But a number of Labour MPs insisted Mr Duncan Smith's departure was driven by the European Union referendum battle.

The main opposition Labour party called for the immediate reversal of what it said were "cruel" cuts to disability personal independence payment (PIP).

In his annual budget on Wednesday, Osborne cut corporation and capital gains taxes and lifted the earnings threshold at which the higher rate of income tax is payable while warning the economy would grow more slowly than previously forecast. The Sun newspaper captured the internal warfare with a headline that alluded to the ancient rebellion against Julius Caesar and - punning on Duncan Smith's initials - warned Cameron to beware the "IDS of March".

"This is not some secondary attempt to attack the prime minister or about Europe", Duncan Smith said in a BBC television interview, adding he quit because he was "losing that ability to influence events from the inside".

'There has been too much emphasis on money saving exercises and not enough awareness from the Treasury, in particular, that the government's vision of a new welfare-to-work system could not be repeatedly salami-sliced'.

Iain Duncan Smith subsequently resigned from his post, saying the planned cuts were "indefensible".

"This is a man who has been responsible for some of the nastiest policies of the nastiest of Conservative governments, all with the support of the Liberal Democrats for five years. I'll say no more tonight but all is not as it has seemed in the past few days".