A Commons backlash against the bedroom tax began in earnest yesterday with MPs voting by a majority of 75 to reduce its impact.

Disgruntled Tory Philip Davies complained that the coalition government “has come to an end” after Labour united with the Conservatives’ junior partners to support back-bench Lib Dem Andrew George’s Affordable Homes Bill by 306 votes to 231.

If ultimately passed into law it would exempt disabled people with specially adapted homes, those with genuine need of a spare room and tenants who are not given a “reasonable offer” of alternative housing with the correct number of bedrooms.

Currently any council and housing association tenant deemed to have “spare rooms” faces a 14-25 per cent cut to housing benefit.

Work and Pensions Secretary Iain Duncan Smith was rarely in the chamber during the three-hour debate, scuttling in sheepishly to defend Tory claims that the Bill would cost £1 billion — a figure that Mr George had branded “speculative.”

A string of Tory backbenchers stood up to deliver lengthy and monotonous speeches in a failed filibustering attempt.

But Labour condemned a “vindictive and incompetent” policy that was not about fairer allocation of homes, as the Tories claimed, but about grabbing tens of millions a year from people on low incomes.

Housing benefit cuts of £700 a year may be “negligible to some of the members opposite,” said Washington and Sunderland West MP Sharon Hodgson.

However, to the vast majority of people “£700 is a significant sum of money and losing it forces them to make choices that many of those opposite could never imagine.”

Fellow north-eastern MP David Anderson said the tax was not really about housing but about who pays for the failure of the banking system.

“When it’s suggested that perhaps one way to deal with this is to introduce rent controls everyone waves their hands in the air and says: ‘Oh no, no — you can’t interfere with the market!’

“It’s the market that’s got people into this situation.

“The people who are paying are the poor, the weak, the vulnerable, the disabled, the dispossessed, the people without a voice.”