I recently presented a school assembly on the subject of homosexuality or, more precisely, homophobia. Having heard that the infamous section 28 of the 1988 Local Government Act did not, after all, apply to teachers, I was at least assured that a police officer would not be asking me to “step this way” at the assembly’s close. Such is the distance schools have travelled in their approach to these subjects, I was also pretty confident I would not find my P45 waiting for me in my pigeon hole.

One of the most enduring legends of British public schools is that they have been “breeding grounds” for homosexuals. Certainly, I reflect now on the striking contrast between the wealth of salacious gossip and cruel invective in private, and the absence of formal public debate in the traditional boarding school I went to 30 years ago. Thank God times have changed.

Or have they? A recent survey by the London Institute of Education showed that homophobic abuse is an everyday occurrence in all types of school - of the 1,000 in the sample, 80 per cent were aware of homophobic bullying. It seems an accepted, if not acceptable, part of everyday school life.

And what about the more well-heeled, tolerant and tightly disciplined pupils in the independent sector? Independent schools have made giant strides towards instilling tolerance and respect for “difference” in recent years. I am, for example, amazed at how much more enlightened students at my own school are towards race, compared with my school peer group. Most appear to recognise that people should be judged by character rather than skin colour.

Tolerance towards racial minorities is one thing, but respect for difference of sexuality quite another. Homophobia may not be endemic in our independent schools, but it is sufficiently widespread, I believe, to produce fear and feelings of isolation among those teenagers still coming to terms with their own sexuality. Frequent expressions from the homophobic lexicon are testimony to this. I find it puzzling that for every pupil who would be horrified to hear one of his peers referred to as a “yid” or “wog”, perhaps another 10 would shrug off the term “faggot”, “fruit” or “bender” as light-hearted and harmless banter.

Homophobic abuse does not touch only those at whom it is directed. It acts as a form of policing to ensure “correct” types of behaviour from everyone, whatever his sexual orientation. Some boys feel they must work hard to fit in with the demands of macho masculinity.

Sensitivity, gentleness, the open display of emotion and even intellectual activity are qualities associated with girls, so rejected. Some boys need to demonstrate their credentials as tough, heterosexual lads. This may be no more than a reflection of the values and prejudices of the wider community, even though gay sexuality has been aired on almost all the TV soaps and in popular culture generally. Politicians and pop stars have come out and been accepted. Many gays are now unashamed of their sexuality, indeed proud of it. These are signs of real progress, and of a society at last starting to banish possibly its most long-lasting taboo. But it has been a change slow to permeate our schools.

I am, of course, aware that puberty is a time of great sexual insecurity and uncertainty for teenagers. They naturally feel more secure by identifying with the majority, and occasionally vilifying the minority. It may also be because residual counter-currents of homophobia continue to run deep. Attitudes will be slow to change in schools if many people continue to argue that homosexuality is a profanity. And as long as bigotry, intolerance, a desire to find scapegoats for society’s problems and a primitive instinct to persecute the vulnerable remain as features of the human condition, homophobia will continue.

Against such forces, it would have been a gargantuan act of self-delusion for me to have left the assembly thinking my few words had made much difference. But at least I had the satisfaction of knowing I had got something off my chest.

Graham Lacey is head of sixth form at Sevenoaks School, Kent