I am always amused by journalists who join the staff of comprehensive schools "undercover" and purport to be horrified by chaotic lessons. I was in the top stream of a grammar school in the 1950s and recall at least three teachers who were incapable of controlling us and in whose lessons nothing was learnt. We were daily assured that we were the worst group of children in memory.
So I am not surprised by a new report from Cambridge University. It found that when asked to identify the most serious obstacles affecting their work, secondary teachers put "poor pupil behaviour" top - ahead of large classes, inadequate resources and government paperwork.
I remember several studies over the past 30 years that came up with similar findings. They reported that what most upset teachers was persistent, low-level disobedience and inattention. Why is this always a shock to academics and journalists? Children are like that. If you work in a school, you have to put up with naughty children, just as you have to put up with drunks if you work in a pub.
Though it is tempting to blame food additives, family breakdown or violent videos, I do not think children have changed much. The change is among adults - a point the Cambridge report picks up when it finds teachers complain they no longer get automatic backing from parents. This is a problem that really has grown in the past 20 years.
Adults once formed a seamless canopy of authority. Children were easily divided. But adults were like a well-disciplined trade union. Not only did they apply a rigid set of rules; they also seemed to have some invisible means of communication whereby they knew, within a bewilderingly short time span, of any transgressions.
When I was about 14, it was reported that I had visited a girl's home while her parents were absent. This fell outside the adult union rulebook. My mother knew about it before I got home, even though we had no telephone. I argued that it was a case of mistaken identity (as it was) but that was to call an adult "a liar" and the rulebook recognised no such category. It is inconceivable that any adult would now report a child's misbehaviour to its parents. "And what if heshe did?" would be the reply. "What business is it of yours?"
The rulebook has gone and the union has disintegrated. It is not just that society has lost common values and standards but also that one section of the adult community - the advertising industry - conspires with children against parental authority, exploiting "pester power" to sell unhealthy foods and expensive toys, and giving children secret codewords so that they can spread the message about these products without their parents knowing.
I support the regulation of advertising, but I doubt we can get the rulebook back. Do we really want it? Members of the adult trade union, remember, had wide discretion to assault children violently and more or less complete immunity from charges of sexual abuse. We may have made the world harder for adults, and for teachers particularly, but we shouldn't forget that, for many children, the old world was a harsh and unjust one.
Peter Wilby is editor of the New Statesman