"Never go back" was a piece of paternalistic advice once offered to me in the late 1970s by an old drinking friend known to me as "John the gangster". The "back" he had in mind consisted of certain louche Mediterranean resorts, swish hotels, dangerous women, and of course prison, elements that had shaped his life as a jewel thief. With no such colour or variety in my background, it had seemed a redundant aphorism at the time. But the better I got to know "John" and myself, I could see that there were occasions when it might apply.

The first of these was a school reunion, framed as a dinner for all former pupils and their partners. There had been no great tradition to this, the school in question having floundered and fallen into decay thanks to government machinations, both local and national, in the 1970s, when state education was a political rather than economic issue. As sixth-form pupils, influenced by les evenements in Paris of 1968, and the civil rights movements in America, my year group had been keen to enjoy the "radical chic" of fomenting change from within the school. Indeed one of our circle began to prowl the narrow streets of the small Lancashire town that hosted the school, dressed as a "Black Panther" with single leather glove, shades and combat jacket, despite the fact that he was emphatically white.

We campaigned for the abolition of the "prefect" élite, arguing that as A-level students we were capable of taking collective responsibility for disciplining our juniors, and eventually succeeded with this gesture to egalitarianism. We were also allowed to form a "Sixth Form Council" that was able to air grievances and make suggestions to the staff about the running of the school. Just five years prior to this breakthrough, the starched-collar headmaster of the time had issued a banning order on Cuban-heeled boots, suede shoes, tab-collar or button-down shirts, identity bracelets and Mod haircuts, hoping to halt the tide of change. But it quickly engulfed him, and his successor was much happier to go with the flow. Our year had stormed the barricades, and would surely live on in history.

But when I finally went back to one of the school reunions in the late Eighties, it was soon made clear from the talk around the tables and in the bar that my g-g-generation was held responsible for various crimes. The abolition of the 11-plus was linked to our radical fervour, as was the collapse in discipline and the eventual mothballing of our 400-year-old grammar school. The worst part was that the criticism came not from the older members, stricken with nostalgia for a lost past, but from men who had been first and second-year "newts" when we'd been leading the "revolution". "Never go back" came quickly to mind.

Yet last week I returned to my old college at Cambridge, St Catharine's, (with an "a", not an "e" like its Oxford counterpart) for a private dinner with its new master. "There's no hidden agenda," he assured the dozen or so old members of various years, and yet there's always been one in the back of my mind.

In 1969, I had been persuaded by my English teacher, Ewart Heywood, a man, as his name might imply, of great liberal wisdom and learning, to apply for Cambridge despite my political ambivalence and provincial reticence. We firebrands were all supposed to go to Warwick or the London School of Economics. Inasmuch as an 18-year-old working-class kid could rationalise the dilemma ­ class-traitor or agent for change? ­ I flattered myself that I was the latter and accepted the offer that St Catharine's made.

It was a pleasant surprise, then, to find not just fellow Liverpudlians but also Geordies, Brummies and Mancunians in the 1971 intake, all from state schools, whereas colleges such as Magdalene seemed to have taken a block booking from Eton. Apart from the fact that it, like all other colleges, refused admission to women, St Catharine's was an open-minded and friendly place. There were still radical undercurrents but most of my activities revolved around playing football, writing for the student paper Varsity and running the college bar. But I was an undistinguished student.

Walking around the college last Wednesday evening, I was therefore impressed by the notices appealing for "quiet" as the examination period was under way, and the air positively dripped with the anxiety of last-minute revision, something I'd managed to "swerve" in my time. But just 30 years on, this is already a different age.

The colleges are co-educational ­ with the exception of Newnham ­ and the vast majority of student places are earned on merit, not on family connection. St Catharine's remains a progressive but hard-working college, with an even greater percentage of state-school pupils than ­ God, there is no other phrase ­ "in my day". Because of this, I'm a minor donor to the college and a quiet evangelist for it as an institution. Nothing in my career has ever been achieved because of "the Cambridge contact" apart from a small overdraft from an old-style bank manager who'd been to Selwyn. But the freedom of mind and time to find my way that I took away with me were invaluable gifts.

Education, both secondary and tertiary, remains a battleground, though the casus belli seems to be more about funding than egalitarianism. This isn't to say that the fight for equality of opportunity is over. The grey-haired old git wandering around main court in a dinner suit may have looked like a classic nostalgist on a flying visit, but believe me, comrades, the struggle continues.

Cambridge looked pretty forlorn on Thursday as the cold wind and lashing rain had the empty punts bobbing in unison by Silver Street Bridge. The market in the square was threadbare too, while King's Parade was windswept and deserted. The tourists, it seems, have yet to turn up in their expected, money-earning droves. With most of the colleges "closed to visitors" because of the examination period, there isn't a lot to see or do. The backlash from foot-and-mouth goes on.

As a sometime television dramatist, it struck me that what Cambridge needs in its tourist portfolio is a police series that will replace Inspector Morse and do for the city what Morse continues to do for Oxford. I'm going to work on an idea now, and offers will be extremely welcome. I can't go into detail, but it involves an archaeologist and ancient crimes. "Never go back" is the working title, if anybody is interested.