Among all the bad ideas on the political agenda, the homeschool contract seems to me to be the most dangerous, all the more because it has the support of people you normally agree with. I was driven to write when I heard that some were even advocating prosecution for parents who failed to attend open evenings.

As a school governor who works with many others across the country, I don’t for one moment belittle the problems teachers have with children who have inadequate home support.

At one extreme you have parents who waylay teachers everywhere, always want the book at home, fret about passing lapses from excellence and are racked with anxiety about fairly minor misdemeanours. They can be quite a problem too.

At the other extreme are parents who seem indifferent to their children’s progress or behaviour, don’t turn up to open evenings, and send children to school too early, unsuitably dressed for the cold, without breakfast or adequate sleep, often not well, and in no fit condition to learn.

I know from contact with governors that it is like looking through a window into hell when a teenager from such a background reaches the end of the road at school and is about to be denied any further forgiveness. You find out a lot about their circumstances and sometimes are privately amazed, not that they have behaved so badly, but that in homes without order, purpose or joy they have not behaved even worse.

Worst of all, their parents often seem to have given up on them. Do what you think best, they say, I can’t do anything with him. For the school there is scarcely ever any adequate alternative. The law didn’t actually say that local education authorities had to provide referral units sufficient to meet the need.

There are often waiting lists of months to see an educational psychologist. Even if teachers had the strength to go on trying, there is often powerful pressure from other parents to remove the violent and disruptive classmates. So in the end schools give up on them too.

It is a privilege to have parents who choose schools carefully, support their aims, maintain an ordered and healthy lifestyle and help children learn. If all children could have that privilege many problems would be solved.

The best schools work very hard to extend this privilege. They go on giving more to those whom life has given less. They offer infinite understanding and try to convince parents whose self-esteem is low that you don’t have to be clever or rich to support your child. Such schools need encouragement, not blame. There is no better way of securing parental support.

What sort of sense does it make to cut the positive support measures and instead try to punish and isolate those who fail? It is, of course, the same philosophy which identifies failing schools but allows the structures of school support to wither. Schools or children, it is a failure culture.

Homeschool contracts cannot be enforced, and I was always taught that unenforceable law is bad law. Having to sign something you can’t deliver only increases the isolation of parents who know that they are failing and may be powerless to prevent it.

Such feelings of inadequacy do not help the child: they only become a new barrier between parents and schools, increase inequalities, and destroy the fragile fruit of so many schools’ efforts to break down barriers. Children already suffer enough from circumstances they cannot choose. Contracts would merely label and isolate those whose parents fail.

The author is the national president of the Campaign for State Education