There was a teacher at my secondary school who was - presumably still is - a deeply unpleasant man. His speciality was punishment, and he seemed to derive a vicious pleasure from punishing young teenage boys. We were fortunate not to have been his pupils in the era when teachers used canes. In his case the playground view was that he took just a little too much interest in this aspect of his work, and in the way of young boys of course this took on an angle involving rumours of gay sex. Did any of us have any real knowledge on the subject? I certainly didn't, he never tried anything like that on me, I was bigger than him. And I never walked in on him in the book cupboard with a third-former among the history books or anything like that. But the fact is he was abusing his position and damaging young lives, I still have nightmares about school today because of people like him, and I know I'm not alone in that.
Could I go to the police? Of course not, much as I wish I could send him into the nastiest jail imaginable. I'm guessing that however much damage he did, he wasn't breaking any laws in what I saw him do, and I can't do so on the basis of playground rumour.
If you're British, you'll probably have guessed why my teacher is on my mind this morning. The story of the moment is that the late 1960s and 70s TV personality and sanctified charity fundraiser Jimmy Savile has turned out to have had a penchant for sexually assaulting young teenage girls.
The shock comes of course because it's not really a shock. I first heard rumours about Savile about twenty years ago when I was working at the wilder edge of the media industry. They sounded like idle tittle-tattle, but we're told for those close to the epicentre it was more than just common knowledge. Others have done plenty of outrage at this both faux and otherwise, where I find the worry is at a more personal level. How much do you have to know before you go to the police?
So in an odd way I understand why Savile survived in a culture of rumours. The people with real evidence - those who walked into the dressing room and found him with a 13-year-old - are unforgivable, but for those who didn't I can see why it would have been very difficult for them to do anything about it. Like my teacher, he was in too unassailable a position.
I wonder how guilty I'll feel though if an ex-classmate of mine ever comes forward with a more serious tale about our teacher.