Image caption Lib Dem MP Andrew George saw his bill move to the next stage

A glimpse of the coalition yet to come?

A Lib-Lab alliance has just voted Andrew George's Affordable Housing Bill through second reading and registered a considerable parliamentary/political coup in the process.

Mr George's Bill would bring in a couple of major exceptions to the government's housing benefit changes - known to their critics as the "bedroom tax."

The Lib Dems (a couple of rebels, including Mr George, excepted) helped vote those changes through in the first place, in the passage of the Welfare Reform Bill, but today they performed a spectacular U-Turn, with back-flip and triple salko, and voted to undo them.

That partially lifts one political albatross from around their neck - a number of their MPs were being clobbered over the issue - and simultaneously puts a new obstacle in front of the Conservatives' cherished EU Referendum Bill.

And Mr George's Bill now has a fighting chance of clearing the Commons.

Filibustering tactics

Let me explain: a big part of today's parliamentary battle was in fact about the downstream effect of sending any private members bill into Committee ahead of the EU Referendum Bill, which is due on the floor of the Commons in October.

Image copyright WPA Pool Image caption Lib/Lab cooperation offered a vision of a different coalition

As the Conservative backbencher and veteran killer of private members bills, Phillip Davies pointed out during the debate this was always the subtext to the debate.

The more bills that are in the system ahead of the Referendum Bill, the later it will come back to the floor of the House for the crucial Report Stage debate. And the more vulnerable it will be to filibustering tactics by its Lib Dem and Labour opponents.

And this is good news for Mr George and those who want to undo the government's housing benefit reforms, because the Conservatives now face a nasty dilemma.

The normal way of killing a private members bill that has survived Second Reading is to bury it in amendments at Report Stage.

Trust eroded

But if the George Bill has a long drawn out Report Stage, there's even less debating time left for the Referendum Bill, later on.

So my bet is that the Affordable Housing Bill will now clear the Commons, to the sound of grinding Tory teeth - and while it might be vulnerable to death by a thousand amendments in the Lords, Labour and Lib Dem peers, plus sympathetic Crossbenchers may see it through to the Statute Book.

And all this may be repeated next week, with Michael Moore's International Development Bill.

And by the time of the Referendum Bill's Second Reading, on 17 October its hopes of success may be forlorn, and the aim will not be so much to pass the legislation as to pin the blame for not passing it squarely on Labour and the Lib Dems.

But meanwhile such a high profile demonstration of Lib Lab cooperation must chill Tory spines and show a little leg to voters lost by the Lib Dems when the joined the coalition.

Collective responsibility may have been suspended within the government today, but trust between its member parties must have been eroded.