THE ‘bedroom tax’ is odds-on to be scrapped for most people affected, after Labour and the Liberal Democrats joined forces to ambush the Conservatives.

A backbench Bill to exempt disabled tenants and those who cannot be found a smaller home – the vast majority – cleared its first Commons hurdle with a majority of 75.

It is now likely to pass into law before the general election, creating the unprecedented situation of part of the Coalition revoking its own legislation.

One furious Tory backbencher, Philip Davies, branded the Liberal Democrats “devious and untrustworthy” – and said the Coalition was now effectively over.

A Conservative minister claimed the U-turn would cost £1bn, but around 70 of the party’s backbenchers failed to show for the vote, despite a three-line whip.

Labour, meanwhile, vowed to press for the bedroom tax to be scrapped altogether when the Bill is scrutinised further in a committee, later this year.

Tom Blenkinsop, the Middlesbrough South and East Cleveland MP, said: “I regularly hear from victims of this cruel policy who are being forced out of their homes, or under mounting pressure from bills they cannot afford.”

Redcar MP Ian Swales, was among all but three Lib Dems who backed the Bill yesterday, having rebelled to oppose it when it was first introduced in 2012.

He said: “I knew that, in my constituency, we did not have enough one and two bedroom properties to cope with the change.”

Nick Clegg – who was at the NATO summit and missed the vote – performed his U-turn in July when, after strongly defending the bedroom tax, he admitted it “wasn't working”.

The Government insisted the measure would free up houses for large families on waiting lists, but critics said the lack of smaller properties meant it was impossible to move.

Nationwide, just 4.5 per cent of tenants ‘downsized’ in six months – leaving the rest hit by housing benefit cuts of 14 per cent (for one extra bedroom) and 25 per cent (where there are two).

The Northern Echo revealed that North-East town halls shelled out almost £6.5m in emergency ‘discretionary housing payments’ (DHPs), mostly to ease the pain of soaring rents.

Both James Wharton (Stockton South) and Anne McIntosh (Thirsk and Malton) were among Conservatives who voted to keep the bedroom tax yesterday.

But the Tories may now be forced to allow the change through to give their own favoured backbench Bill – on guaranteeing an EU referendum – a better chance of making progress.

Andrew George, the Lib Dem behind the Affordable Homes Bill, argued social housing tenants should be exempt until they receive a “reasonable offer” of alternative, smaller accommodation.

Disabled tenants would not be affected if they needed an extra room for “genuine medical reasons”, or if the property has undergone major adaptations to help them live there.