DAVID Cameron refused six times to say whether or not he could give a “cast-iron guarantee” that no-one would be worse off from next April following the planned £4.4 billion tax credit cuts.

Jeremy Corbyn failed to pin the Prime Minister down and was told he would have to wait a month to learn the answer in George Osborne’s Autumn Statement on November 25.

Following defeats in the House of Lords, the Chancellor has promised to soften the introduction of the cuts without reneging on the principle of the policy; but no details have been forthcoming.

Critics of the policy insist some three million families across the UK, including 350,000 in Scotland, face losing £1,300 a year because of the cuts. But the Government claims the losses will be more than offset by other policies such as free childcare, the National Living Wage and a rise in the tax-free personal allowance.

Today, Unison, the trade union, will seek to put moral pressure on Conservative backbenchers, ahead of another Commons debate on tax credits this afternoon, by writing to them saying this will be their “chance to speak out for those, who work hard, raise their families and do the right thing”.

Last night, Mr Osborne was given a rousing reception when he addressed Tory MPs at a meeting of the 1922 Committee to reaffirm the Government’s determination to get the £200 billion annual welfare bill down. One MP said the mood had been "100 per cent supportive".

Question-time in the Commons was dominated by the tax credits controversy with the Labour leader using every one of his six questions to try to secure an answer from Mr Cameron. But each time the PM sidestepped the question.

Mr Corbyn asked, following the rebuff from the Lords, if the Tory leader could “now guarantee to the House and to the wider country that nobody will be worse off next year as a result of cuts to working tax credits?”

To Tory cheers, the PM replied: “What I can guarantee is that we remain committed to the vision of a high pay, low tax, lower welfare economy…As for our changes, the Chancellor will set them out in the Autumn Statement.”

When Mr Corbyn repeated the question, he received the same reply. Mr Cameron referred to his party’s election manifesto promise of reducing the welfare bill by £12bn.

“It is an important point because every penny we do not save on welfare means savings we have to find in the education budget, the policing budget or the health budget.”

The PM noted how the Labour leader had “opposed every single welfare change that has been made. He does not support the welfare cap; he does not support the cap on housing benefit; he does not think that any change to welfare is worthwhile”.

He added: “If we want a strong economy, if we want growth and if we want to get rid of our deficit and secure our country, we need to reform welfare.”

Mr Corbyn claimed Mr Cameron was now losing support over tax credits from people and newspapers, which had usually supported him; particularly as he said during the General Election campaign he would not cut tax credits.

But the PM insisted what he said during the election was that the “basic level of child tax credits would stay the same” and it had.

He argued that it was a strange set of events when, after MPs had voted for the cuts five times, Labour was left defending and depending upon unelected peers. “We have a new alliance in British politics: the unelected and the unelectable,” declared Mr Cameron.

Meantime, Iain Duncan Smith, the Work and Pensions Secretary, told MPs that the Scottish Government could, because of new powers, introduce top-up payments to make up for any shortfall benefits claimants faced because of future cuts to tax credits.

He told the Commons Work and Pensions Committee that it would be "wholly within the power of the Scottish Government to add additional payments" but stressed: “That money would have to be raised in Scotland."