John Rentoul: The troops gladly helped Kelly fend off the Tories. But she shouldn't fool herself

The novelty of David Cameron's support has not yet sunk in

Ruth Kelly is in mortal peril. If one of her ministers has signed a letter saying that a sex offender was allowed to teach and it turns out that they have since committed an offence at school, she is done for. For a moment, it looked as though Kim Howells had deflected the media swarm. In the whodunnit case of which minister had signed off permission for Paul Reeve to take a job, however briefly, as a PE teacher in Norwich, it turned out that it was Howells. Conveniently, he has since moved to another department. Meanwhile, however, other cases are being reported, and it may be weeks before clarity emerges from the murk, during which time Kelly is vulnerable to the charge that she does not really know what is going on.

It is a strangely non-political story. This may seem fitting, because Ruth Kelly must be one of the least political education secretaries to hold the post. It seemed strange, when Tony Blair appointed her, just more than a year ago, that he should put someone so managerial, however clever, into such a profoundly ideological job. The ideological passions that swirl around her mean that almost any story about schools is political. The paedophile scare story would have held the headlines anyway. But the fact that so many Labour MPs dislike the schools White Paper gave journalists the chance to get the word beleaguered into their first paragraph (if they could spell it; embattled, if they couldn't).

It gave the BBC an excuse to run "impartial" speculation that Kelly might lose her job in the cabinet reshuffle (to fill the Chancellorship of the Duchy of Lancaster, vacant since David Blunkett's resignation), which Downing Street has been promising "soon" since November. There is, of course, no connection between employment screening for paedophiles and the reform White Paper, except that both are the responsibility of the same department.

Yet an ideological split in the governing party allows lazy journalists and lazy politicians to substitute word association for thought. They know that Kelly is already at bay on the issue that touches the most sensitive parts of the Labour Party: selection. The split is serious. How could it not be when Labour's former leader, former deputy leader and present deputy leader all oppose the current leader's schools policy? But it neither threatens the legislation nor Kelly's position. The novelty of David Cameron's support for the White Paper has not yet sunk in. He means it: the Conservatives are not going to vote against the Bill. It will therefore pass into law. The only question is how big will be the Labour rebellion, and how embarrassed the Prime Minister? As Blair does not like being embarrassed, he will make concessions. Most importantly, it can be predicted that he will write in his own blood: "There will be no extension of selection." But the essential reform will be carried through, to allow outside sponsors and new providers of state schools.

It is alarming that Neil Kinnock, Roy Hattersley and John Prescott all feel so strongly about defending the phantom of a comprehensive education system that has never existed. The appalling negativism of their policy was encapsulated in the words of the Deputy Prime Minister before Christmas: "If you set up a school and it becomes a good school, the great danger is that everyone wants to go there." That should have been the end of it, a prospectus swept away on a wave of ridicule. But no: this is an emotional spasm, not a rational debate.

As important as the words of Prescott, though, are those of Gordon Brown. "The combination of our reforms is to give greater opportunities to every child," said the Chancellor in November. "Greater choice for parents and all these things are part of that educational reform. That's why we are pushing forward with the new White Paper. When the reforms are explained to people, they will see they are the right thing to do."

Brown the strategist knows how dangerous Cameron's bear hug is, and how easy it would be for Labour to duck out of it by lurching to the left. He also knows that Cameron's speech last week pledging not to return to the 11-plus concealed the threat of a patchwork extension of selection. Yet Brown the politician, it would seem, has assured Prescott that he can stay on when Blair finally goes. If true, this would be a terrible admission of failure on Brown's part. It would mean that he could not be sure of securing the party's support for a young English candidate, preferably female, to counter Cameron's youthful appeal.

There can be no doubt that, if and when Brown takes over from Blair, he will continue New Labour's reforms. Indeed, he will intensify them. That is necessary to meet the threat from Cameron at the next election, but it is not sufficient.

What ought to be worrying the Labour Party is that Brown has done nothing since the Tory leader was elected that convinces anyone he - unlike Blair - has got the measure of Cameron. All this stuff about Britishness works in the mechanical sense that it produced a picture of Brown next to one of the Union flag (in case its readers had forgotten what it looked like) in yesterday's Daily Mail. But it is simply a rehash of what he has done before. As for the idea of a British Day it is, well, just not British.

That is the broader context of Ruth Kelly's difficulty. If her position is under threat, it is purely because of the paedophile issue and because she appears to have allowed the urgency generated by the Soham murders to gush into the sand of her department's bureaucracy. She is not under threat because of the controversy surrounding the schools reforms. It is true that she has not done a particularly good job of selling them to her party. It is easy to imagine a more political politician - John Reid, for example - promoting the White Paper as the embodiment of the egalitarian dream of Anthony Crosland. She is getting better at it, but it doesn't matter too much because she is in the right place in the big picture, which is that Blair and New Labour still carries all before it.

It was interesting that in the House of Commons last week, answering questions on the sex offenders policy, Kelly enjoyed surprisingly vocal support from the Labour back benches. On a non-political issue they reverted quickly to default behaviour, which is to defend one of their own from opportunistic assault by the Conservatives.

Yet that is the issue on which she is vulnerable, and not the political issue that divides the Labour Party.