Horrible it is to pass judgment on a parent’s private decision about the education of a child, and one with special needs at that. Horrible, but important. Had Ruth Kelly not been prepared to accept public discussion of her decision to send her son to a private school, she could have chosen to pursue an alternative career. She could have resigned from the Government at least, if not from her seat and the Labour Party.

Which is what she should have done, because she has breached the fundamental principle of the Labour Party. Read the key sentence in the new Clause Four of Labour’s constitution, that section inserted by Tony Blair to enunciate the founding principles of new Labour and considered so important that it is printed on every party membership card: “It (the Labour Party) believes that by the strength of our common endeavour we achieve more than we achieve alone, so as to create for each of us the means to realise our true potential and for all of us a community in which power, wealth and opportunity are in the hands of the many, not the few.”

All parents who move their children from state schools to private education breach that principle in the most fundamental way. Each time an articulate, ambitious parent removes his or her child — and therefore the parent as well — from the state system, it damages the chances of every child that remains in the local school. The offspring of the aspirational middle classes (and, increasingly, of immigrant families) are absolutely central to a school’s success; nowhere is “our common endeavour” more important than in joining forces to improve outcomes in individual schools. And that is central to all that a democratic socialist should stand for, because a good educational start offers the key to everything else; it is opportunity. Nothing else comes close.

It is because people on the Left know this that they send their children to private schools so reluctantly, and find it so excruciating to talk about once they have done so. The guilt-ridden silence of most of The Guardian on the subject of Ruth Kelly — the silence of nearly all its writers on comprehensive education generally — is entirely eloquent. The paper carried the story in just eight paragraphs on page nine on Monday.

That silence, in The Guardian and elsewhere, is damaging. One of the big problems when influential people in public life send their children to private schools, and feel guilty about it, is that they stop campaigning to improve education, not because they do not care about the life chances of the rest of the country, but because they fear they have no answer to the accusation: well, why don’t you send your kids there, then? If you believe in “the strength of our common endeavour”, there is no defence. That doesn’t make the question unanswerable. The true answer — and one I sympathise with, incidentally, without much liking it — is, I put my child’s interests before my political convictions. Which is tricky if you are a Labour supporter or member. Or worse, a Labour MP. Or even worse, a Labour minister. Or, worst of all, a Cabinet minister. Or, unbelievably so worst that it’s beyond consideration, a Labour Education Secretary who, possibly even while still in post, seems to have secretly turned her back on the local state school and jumped through the hoops of selection for a highly elitist school, whose website boasts that it is “the only preparatory school in the United Kingdom to have as its main purpose the preparation of dyslexic and/or dyspraxic boys for Common Entrance and other entrance examinations to mainstream independent senior schools”.

Oh, suggest Ms Kelly’s anonymous friends, but the former Education Secretary only took advantage of a service available to parents of other children with special needs . . . Except that it’s not available to other parents.

For obvious reasons, we do not know all the details about the Cabinet minister’s son, but there has been no suggestion that he is severely dyslexic, nor does he seem to be statemented. That process alone can take years, and often fails even then to bring the additional financial support a child needs for properly trained assistance or transfer to the private sector.

If breaching the most fundamental principle Labour holds is not enough, I’ll tell you why else Ms Kelly should resign: because this Government removed from other children of poorer families the opportunity to enjoy the benefits of private education by withdrawing the Assisted Places Scheme. It even withdrew assisted places funding for children already receiving it, when they moved from primary to secondary level, despite initially promising not to. And I don’t remember Ms Kelly campaigning to have that opportunity reinstated when she was Education Secretary.

Nor do I remember her campaigning to improve special needs provision in the state sector. When Maria Hutchings, the mother of an autistic son, campaigned with the Conservatives for better special-needs provision during the last election campaign, Ms Kelly, Education Secretary at the time and pursuing a policy that encouraged inclusion in mainstream schools, accused Ms Hutchings of trying to “grab the easy headline”. Well, Ms Kelly has learnt the hard way how easy a headline can be to grab.

I have always liked Ruth Kelly. I find her interesting, thoughtful, entertaining, and although I don’t agree with her rigid Catholic principles myself, I admire her for sticking to them even when they have got in the way of her career. She is a curious fish in a dull grey sea. Still I think, regretfully, she should resign.

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