Our former pupils, though, live in a land of forever 18, unless we've maintained contact, or collided in the supermarket: "Ere, didn't you use to be Mr McPartlin?" I have recently had to come to terms with the tragic early deaths of two former pupils. Bad enough for death to come in the 20s or 30s, but even worse when your funeral memories are centred on the deceased as a 14-year-old on a residential trip, splashing in the waters of a Highland burn. Or of a poised and compassionate young woman promoting the sixth-year's charity fund-raiser to a second-year assembly.
We start something we can never finish, as teachers, when we initiate the business of compiling a profile of our pupils. As a colleague remarked, it's a bit like lighting the blue touch-paper and then retiring before the rocket has reached orbit. It is possible, I suppose, to deduce the rough trajectory of the final flight, but it is far from an exact science. I expect most teachers ponder their students' fate from time to time.
There is, thankfully, a lighter side to this particular unfinished business. Occasionally, fate takes a hand and the final piece of the jigsaw falls in place. If you're in luck, you may receive that overwhelming feeling of contentment that comes when you are proved right in your outrageous prejudices. And so it proved last month.
I received, as a birthday present, from my oldest friend, of more than 30 years' standing, a newspaper cutting concerning the lad who had been head boy in our final year at school. Given it was the late sixties, it is not surprising that he had been elected to that position as a direct result of his bolshie attitudes, and a certain flare for self-promotion.
He it was who instituted a link with the local girls school and ensured regular meetings under the banner of "Sixth Form Cultural and Social Society". He maintained a year-long guerrilla campaign against the ethos of the school, and in particular against its visible form on earth, the headteacher.
The highlight of his time in office must have been speech day, when there was a Keystone Cops-type dash around the backstage area of Liverpool's Philharmonic Hall as the headteacher sought to keep apart our illustrious head boy and the archbishop, lest anything profane be said.
What joy it was then to read the cutting from last month's national press. Our ex-head boy has risen to giddy heights in the world of higher education. In an article on "My Week", he managed to mention meeting Tony Blair, several famous actors and the fact that he flew to a major European capital every other weekend to be with his partner who lived there. He didn't seem to have changed a bit. But then there was the photograph.
The suit was ridiculous, the earring, on a 45-year-old, looked distinctly odd, but it was the haircut that sent me way over the top. A mixture of Rod Stewart and Dusty Springfield at their worst, it was the perfect illustration of a complete lack of self-awareness. So delighted was I at this sudden justification of everything I'd ever said about him in the sixties, that I felt compelled to burst into verse: Schadenfreude I believe it is called; I got down on my knees and thanked God I was bald.