She held a number of rather wild parties. She also entertained me one evening to dinner alone. As the lawyers used to say, no impropriety took place; I intended none and, if she did, I wasn’t aware of it. Nor was I aware of any censure from the school authorities or of any suggestion that the dinner should be kept secret.

I mention all this because, during the summer holidays, it was scarcely possible to open a newspaper without reading some denunciation of Mary Beard, professor of classics at Cambridge University. On Times Online, she recalled a long-dead Latin don who was notorious for his wandering hand.

“One can’t help deploring the abuse of male power,” she wrote. “But one also -honestly - can’t help feeling a bit nostalgic for that, now outlawed, erotic dimension to (adult) pedagogy.” The nostalgia derives, as I understand Professor Beard, from the loss of a close association between intelligent people of different generations.

Professor Beard thought she was being “nuanced”, and the Daily Mail quoted her making a deliciously donnish distinction between feeling nostalgia and “saying that this is now how I want it to be”. But the papers don’t do nuance. The fierce negative reactions of the National Union of Students and assorted professors of gender got the better press.

You may dismiss this as a typical silly season story. But it raises questions which go beyond Oxbridge classics dons. University teaching is not the only area that may have lost something from our anxiety to guard against sexual harassment, paedophilia or just “inappropriate contact”.

Teachers’ unions advise members to avoid ever being alone with a pupil.

Only close relatives (and not always they) dare show a child physical affection. Scouts and other youth organisations struggle to recruit volunteers. And I doubt that, if I were now 17, a young, single teacher would invite me to dine alone at her home. Since I had never previously dined out, I suppose that would be my loss.

It is right that we now abhor child abuse and no longer tolerate abuse of authority for even low-level sexual gratification. But do we need to go so far? Can’t we forbid the sex but still allow intimate relations between teachers and pupils, adults and children? Even as I write that sentence, I realise that “intimate relations” is itself ambiguous and that, no, we probably can’t have our cake and eat it.

We live in a highly eroticised culture. Sex screams at us from advertising, television, cinema, music, magazines, websites. We have pushed the boundaries of what is sexually permissible - what we do, who we do it with and how we talk about it - to limits that would have astonished our grandparents. We have turned almost everything and everybody into a potential object of erotic attention.

That, I think, explains why we feel the need to be so firm about where the limits do lie, even if that entails hypocrisy. Children are off limits, despite the marketing of sexually explicit material and sexually provocative clothing, even to pre-teens. If you are a teacher, pupils of any age are off limits. If you are a boss, your subordinates are increasingly off limits.

It is precisely because so much is on limits that we have to affirm, almost to the point of hysteria, the things that are not allowed, and probably never should be. That is the price we pay for almost complete freedom of sexual expression and behaviour. But we should recognise that it is a price, and we should allow Professor Beard her nostalgia.