The Prime Minister received a huge boost in his battle over controversial education reforms yesterday when former Education Secretary Estelle Morris dropped her opposition to the policy.
Lady Morris, former MP for Yardley in Birmingham and now a member of the House of Lords, said rebels had "won" their battle with the Government after securing concessions.
She was one of the leading opponents of the Govern-ment's Education Bill within the Labour Party.
Her status as a former member of Tony Blair's Cabinet, who spent much of her political career specialising in education issues, and someone who had never before rebelled against the Government, meant her words carried enormous weight with Labour backbenchers.
Last year she helped launch an "alternative White Paper" setting out objections to the Government's plans, which include creating a new category of "independent state schools" called trust schools.
The document, which was signed by around 90 Labour MPs, called for tougher controls to ensure the new schools were not allowed to select pupils and effectively become grammar schools.
It also warned that taking schools out of local authority control would isolate colleges from each other, instead of encouraging them to work together.
Since then, Mr Blair and Education Secretary Ruth Kelly have agreed to include a strict ban on selection within the Bill, giving it legal force.
They have also agreed that councils will still be allowed to open new schools, with the permission of the Secretary of State.
The Education Bill will have its second reading in the House of Commons next Wednesday.
This will be the crunch vote, in which Labour backbenchers could oppose the Bill. However, even if the rebels stand firm, Mr Blair could win the vote with support from Conservative MPs.
Ms Morris said: "There is a danger in politics sometimes that you don't realise when you have won, and we have won."
She added: "If I was an MP I would vote for a second reading. I am not saying this because I have been asked to, or because I am worried the Government will be defeated."