If Ruth Kelly has not enjoyed the row in the press and Parliament over sex offenders in schools, she ought to be asking herself what future political banana skins she is strewing with her white paper proposals.

Ms Kelly should not be the one to decide who should be barred from the classroom. It was her predecessor in the first Blair government, David Blunkett, who insisted on retaining personal responsibility for child protection when decisions about who was fit to teach in all other respects were passed to other agencies.

Quite why Mr Blunkett believed ministers were uniquely qualified for this, he did not say. But it was entirely in line with the obsessive controlling tendencies of recent governments - both Tory and Labour - as they strive to demonstrate their grip on education.

This goes way beyond child protection. In almost every ministerial utterance and every piece of education legislation over the past two decades, education secretaries have either sought more powers over operational matters affecting schools or behaved as if they already had them.

The result is that whenever anything now goes wrong in schools, it is the Education Secretary who finds herself under attack and forced to respond, whether it’s her responsibility or not.

Even in Whitehall this has been noticed. When Sir Richard Wilson, the former Secretary to the Cabinet, retired in 2002 he remarked that the tendency for political parties to maintain a permanent level of campaigning between elections had brought about what amounted to a change in our unwritten constitution. Central government, he said, “is now held responsible by the public for the quality of services delivered locally even though statutorily and constitutionally they are not primary responsibilities of central government”.

Ms Kelly is now placing the protection of children (and of her career) in the hands of “experts”. An arm’s-length agency will determine who is fit to teach. But as experience has shown (and Ms Kelly may yet find), once the press and political opponents scent blood, all the experts and arm’s-length bodies in the world may not save a minister’s neck. After all, who appoints such bodies?

Labour seems to have learnt nothing from the unseating of Estelle Morris as education secretary. She was fatally weakened by a similar media eruption over A-level results.

Unlike Ms Kelly and sex offenders, Ms Morris was not even responsible for setting the standards for A-levels. Indeed, one of the ironies was that the row began with the minister trying to assure the public she had not interfered for political advantage in the grading of A-levels. But it ended in her departure because, among other things, she was held not to have intervened effectively enough to ensure they were fair to students. She was damned if she did and if she didn’t.

Exam standards then (as now) were already in the hands of an arm’s-length body: the Qualifications and Curriculum Authority, with legions of experts and led by Sir Bill Stubbs, one of the world’s foremost education administrators. Standards were further underwritten by the independent exam boards.

None of this saved Ms Morris. Or Sir Bill. The only principal players not to lose their jobs were in the exam boards where the grading decisions causing all the trouble had been taken.

Invoking the mystic power of “experts” calmed things down for Ms Kelly last week. But if she now prevails with her White Paper plans, her legacy will be a series of similar public relations traps for her successors.

Take the idea of independent state schools. They are, of course, a contradiction in terms. They cannot be both independent and state-provided.

Yet, since the whole point is to make them free to be different, then a few at least are likely to do things deemed inconvenient, unfair or downright unreasonable by some of the public they are supposed to serve (particularly by any they decline to serve).

So what will happen every time a contentious exclusion catches the Daily Mail’s fancy? Or when a flagship academy founders amid acrimony or incompetence? Or when MPs are besieged by parents whose children have failed to get their place of choice (or any place at all) in the free-for-all of secondary transfer?

Will a future Ms Kelly say these are matters for the local authority to sort out? No, because they won’t be. Will she say self-governing schools and academies are independent and these are not matters for her? No of course not, because they are provided at public expense. So she will be called to account for their actions.

Is the House of Commons or a TV studio really the best place to sort out the rights and wrongs of an individual’s exclusion? Or a child’s failure to secure a school place? Or a row between governors and head in a self-governing school?

Yet these are where ministers, with the media and political opponents in full cry, will find themselves once again under pressure about operational decisions for which they have not the competence, time or (as often as not) any effective legal powers with which to intervene.

Bob Doe edited The TES from 2001 to 2005