Split personality? Are you talking to us?

So there we all were, 25 years on, falling apart. Some more than others; some in different ways. Some had fallen upwards, into a sort of careful cultivation of order, prudence and prosperity, usually called "sensible" because it can only be achieved at the expense of all sensibility. Others had fallen downwards, into the gulf left when they had abandoned the expectations so carefully instilled in them during their time here, at Cambridge.

Twenty-five years on, the place seemed smaller, shabbier. Had we got bigger? New Court seemed no more than a hand-span across; my old rooms (now the college "Development Office", no doubt complete with a Development Officer, the Development Officer's jargon, and Development Plans) seemed too constrained to have sheltered me for what, in my memory, was a Saturnalia of unfettered delight and indulgence. I couldn't have lived in there, surely? There wouldn't have been room.

There wouldn't have been room for the grand piano. There wouldn't have been room for my life-sized model of Mrs Andy Capp, or my Byzantine thurible, burping clouds of fine Rievaulx incense. There wouldn't have been room for my books and my records and my terrible paraphernalia: a velvet cape, a cavalry sabre, a model aeroplane which never flew, stacks of organ music, an 18th-century rosewood flute, my two big boxes of theatrical make-up, my collection of raucous after-shave lotions, my love-letters, my pornographic magazines, my personalities.

I had so many personalities in those days. I was a great actor, modelled upon Sir Ian McKellen, with whom I had been in love since my early teens. I was a world-renowned baroque musician, modelled on Nicholas McGegan, with whom I had been in love even longer. I was the heir to Dryden, a glittering pocky malcontent holding court in the bar, sought out for my rapier wit and the scarifying precision of my epigrammatic satire, done on the hoof. I was a celebrated anatomist - scholarly, ascetic, vaguely Scottish (in my anatomical phase I was delighted when I grew a beard and it turned out be curly and reddish); I was a Nobel laureate, the greatest synthesist of the unfairly-opposed Arts and Sciences, straddling the Two Cultures like a polymathical Colossus.

I was a lover, too; a tremendous lover, into whose arms women would melt with tiny sighs (sobs, almost) of transcendent delight as their lives were illuminated in a way they had always yearned to find but given up hoping for. And I was a barfly, one of those men whom no woman can ever hope to control or amend, devil-may-care, tousled, dishevelled, negligent of my dress, but with one of those pure, hard, gem-like flames you read about, burning within.

Mostly, these personalities were not attended with much success. Exhausted by the daily burden of deciding who I was going to be each day, I skipped lectures, missed meals, survived on a diet of beer, Jacob's Cream Crackers, baked beans and Branston pickle, the only staples you could get (on tick) from Bert Lawrence or his assistant Stringer at the buttery hatch. Presently I reached such a state of degradation that I would rarely rise until tea- time. Having spent the night pretending to be one person, I would then get up and pretend to be someone else entirely.

One of the things about the old idea of a university - not the modern, Thatcherite one, where you go to learn how to be a useful citizen, have all the Ideas knocked out of you, and, most important of all, get deep into debt and thus incorporated into the dirty little machine which runs the economy and ruins lives - was that you could try on different personalities to see which one fitted you best. But most people had some idea, at any rate, of what sort of things suited them. I had no idea at all. I was like a lunatic in a department store, one moment in Gent's Natty Suitings, the next in Ladies' Lingerie, even, at odd moments, to be found wandering around the Haberdashery department with a bucket (Hardware, Lower Ground Floor) on my head.

But seeing all these men, now in their forties, many distinguished, some unchanged, some unrecognisable, some clinging on, some smugly prosperous, I felt oddly diminished. At one stage I had tried on the personality of Writer (I think it came after Doctor, Priest, Naval Lieutenant, Snob, Catholic Husband, Sexual Deviant and Cocktail-Bar Pianist) and somehow it just stuck. I didn't choose it at all; there was no vocation or compulsion; if nobody paid me I would never write another word. But ... it just stuck. The wind changed and that was that.

Perhaps it's something which just happens. Nature won't let you fanny around pretend- ing to be everyone for ever. The door closes, the lights go off, your name goes down in the little book and there you are, identified, categorised, label round your neck like a refugee from Dreamland: retired inspector, Hong Kong Harbour Police. Wine merchant. City solicitor. Newsagent. Psychiatrist. Schoolmaster. Hack.

We had so much promise. "You are the cream of your generation," we were told, but if we were the cream - C&A executive, manager at Shell, barrister, industrial chemist - what happened to the curds? The whey? And was it really so much promise, or was it more a threat, those three or four years lining up to squat on the rest of your life with the sense of potential unachieved?

One consequence of the attempt to synthesise quantum mechanics and relativity is this: that maybe the universe divides at every point a decision is made. It is possible, in some spinning, icy world of condensed symbolic logic, that I am living all those lives that my wishes never led. And not just me; you, too. This 25-year reunion was not with the people I was at university with; it was with all those old transient selves of my own which never quite made it. I could see them all, looking hopefully at me from the window of my old rooms on G staircase. I had let them down, and couldn't quite meet their eyes. !