Chancellor George Osborne has backed down and promised to set out measures to help people hit by tax credit cuts following a double defeat on the issue in the House of Lords led by a former leader of Norwich City Council.

Peers backed a motion by a majority of 30 delaying the cuts until the Government responds to analysis of their impact and considered 'mitigating action'. Then minutes later the Government was defeated a second time, this time by a majority 17, on Labour peer Baroness Hollis' motion to delay the cuts until ministers come forward with 'full transitional protection' for those affected for at least three years.

Peers defeated the Government despite ministers' warnings that defeat would trigger a constitution crisis.

In a huge turnout for the votes, Labour imposed a three-line whip and reported the presence of Tories not seen in the chamber for years. But it was not enough to save the Government from defeat over a policy which has sparked calls for a re-think from Conservative as well as Opposition MPs.

Lady Hollis, a former work and pensions minister, urged peers to 'keep faith with struggling families' by delaying controversial cuts in tax credits.

She told the House of Lords that her amendment to the regulations was a 'delaying motion' and not 'fatal' to the Government's plans.

'Essentially, the cuts would apply to new claimants only,' she said, in the highly charged debate on the cuts.

Denying the move 'trespassed' on the financial privileges of the elected Commons, she said this did not extend to statutory instruments like the one before the House.

And she dismissed suggestions that voting for a delay would trigger a constitutional crisis, claiming this was a 'fig-leaf' for the Government's counter-claims.

'We can be supportive of the Government and give them what they did not ask for - financial privilege. Or we can be supportive instead of the three million families facing letters at Christmas telling them, on average, they will lose around £1,300 a year.

'Those families believed us when we all said work was the best route out of poverty, that work would always pay.'

Lady Hollis cited the case study of the Norwich-based Tony and Jacinta Goode. She said Mr Goode was in full-time work, earning above the living wage, and Mrs Goode was the carer of two substantially disabled children.

'They are exhausted. Their Christmas letter will tell them that they will lose £60 a week, or £3,120 a year. That is £3,120 from a family where he is in full-time work and she is caring for two disabled children. We do not need to do this to them.'