utumn is the season of fear in the schools. Behind the mists lurk innumerable hazards; mellow fruit can be a killer. Conkers trigger nut allergies or cause physical injury. Soon, if snow falls, threatening the perils of snowballing and improvised skating in the playground, headteachers will tremble again.

Summer brings no relief as hard balls fly across playing fields and the sun fries youthful skin. Worse, enthusiastic teachers may take their charges camping, swimming or climbing. The threats to life and limb and the opportunities for lawyers are endless. Better to insist on headgear during the conker season, to ban snowballing and to keep children indoors, taking tests, throughout the summer term.

David Bell, chief inspector of schools in England, advises that “the benefits of outdoor education by far outweigh the risks of an accident occurring”. Statistically, he is right: Britain’s compensation bill is low by international standards and the estimated pound;100 million paid out annually on school-related accidents is about 1 per cent of the total.

But it is all very well for Mr Bell. Chief inspectors, like cabinet ministers and captains of industry, do not get blamed when accidents occur.

Fears of legal action, and even criminal proceedings, are for the little people, working at the front line. Inspectors and politicians demand more adventure in schools, but are nowhere to be seen when some poor teacher is pilloried for a moment’s carelessness or inattention.

I agree with those who argue that, by being too protective of children, we stunt their development. But people rarely pinpoint the reason. It is not that we have become soft or decadent or that, having conquered diseases that really did threaten children’s health, we have chosen to fuss over trivial risks. Rather, it is that children themselves are more precious, not only to parents but to society as a whole.

In Britain, couples now rarely have more than two children, and many have only one child. This pattern is common across the industrialised world: in Italy, the fall in the birth rate is so steep that, according to one calculation, Italians will be extinct by the 22nd century. Moreover, people now bear their children at an age when fertility is rapidly declining; if a mother loses her only child to an accident on a school trip, there is a high chance she will never have another.

The implications are momentous. I do not wish to belittle the grief that any parent feels at the loss of a child, even if she has a dozen others and can bear a dozen more. But grief heals more quickly if there are others to care for, to love, to cheer you up and divert you. The loss of an only child (or, given the likely effect on its sibling, the loss of one from a two-child family) leaves an almost unimaginable gap.

No wonder parents are so anxious and no wonder they feel that, if somebody else was at fault, that person should be held to account. And given the costs of raising children - particularly in the mother’s foregone earnings - parents may reasonably feel they deserve compensation.

For society, too, all children are now made of gold. By 2050, it is estimated, there will be 35 million fewer children in the world than there are now, and 1.2 billion more over-60s. We are entering an era where an ever-declining number of productive workers will have to support an ever-growing number of old people.

I know the problems of over-population. But declining population creates problems too. The compulsion to wrap children in cotton wool and protect them from falling conkers is one of them.

Peter Wilby is editor of the New Statesman.