It was my girlfriend who stopped my indulgence. It’s either me or that churchwarden, she said, bitter about the way I really adored that pipe and spent hours trying to clean it, when pipe cleaners were never quite long enough. So I married her and forsook the churchwarden. And, of course, I’m delighted I did. But I miss the habit dreadfully. I can still remember the joys of that first pipe of a morning when a few deep lungfuls of Gold Block set me up for the day. A pinch of snuff in between lectures and the air seemed perfumed and promise crammed before me. And the delight of rolling your own of a summer evening: the tin box, the Swan Vestas, something to do with your hands.

The trouble with some teachers is they’ve never had self-indulgent, frivolous habits in their past so they don’t understand the pleasure they bring. How can any child get excited by a text message on his or her mobile phone? Maybe, teacher, if Alexander Graham Bell had invented the telephone before you were a kid and you’d had one, you’d know.

But worse than that are the zealots: the teachers who’ve been there, done that and given it up. They have a curious mixture of guilt and smugness about their past and are eager to stop others from going the same way. They’re making a vicarious purge of their weaknesses. I remember hearing the jazz musician George Melly on television talk about giving up smoking. He remembered having seen non-smokers frown at him through the haze of his tobacco smoke and he vowed he’d never be one of the self-righteous newly reformed. Instead he’d remember what pleasure the habit once gave him. And he’d feel compassion for those who were hooked.

These zealots have contempt for the weaknes in others because in it they see themselves. I was once like you, a slacker, mind stuffed full of cotton wool. But I overcame it. And look at me now. I’m a teacher.

But there’s a third category, the ones who thrive on chutzpah, the ones who did something once and have crowed about it ever since. There is something obscene about William Hague boasting publicly about how many pints he could sink in his youth. I suppose he’s the political equivalent of the worst of all teachers: boring, self-satisfied, pleased that he was a bad boy, once. There’s something that makes me uneasy too about all those MPs who have been so eager recently to tell us they smoked cannabis, once. It’s self-congratulatory. Like me, standing here, posing with my pipe I suppose. It has the whiff of danger. Some people hang-glide, some climb Everest, some take illegal drugs. I did none of these, although I did smoke a pipe and take snuff. But I don’t boast about it in class or use it to woo the electorate.

I’ve paid a nostalgic visit to 74 Charing Cross Road. The huge scales have gone. So has the lovely, eccentric old man who used to serve me. The cigar room remains, with its panelled walls and ironic No Smoking notice on the door. It’s not quite the place I remember. The little round snuff boxes are still there, and my old favourite, S P Best, is still among them, but they have stark warnings on the front and back, all the starker for being so matter of fact: Causes cancer; made in England. Only a fool would sniff snuff today.

And it goes without saying that if Sir Walter Raleigh came back from his travels tomorrow and said, “I’ve discovered what you can do with tobacco: turn it into a fine powder and snort it up your nose”, the Government would ban it. And anyone caught snorting behind the bike sheds or having an indulgent frisson with a churchwarden or a mobile phone would be given an instant detention.

Quite right too. But would it be punishment without understanding?

Richard Hoyes teaches at Farnham College, Surrey. Email: richarddeaubenay@yahoo.co.uk