I left Paisley Grammar in 1969. In June, more than 40 of us celebrated that anniversary. Animated conversations, photographs and school magazines stirred memories but also illuminated the experiences which had made us, the last selective generation, the people we are. With (nominal) fees, higher entrance qualifications and archaic traditions, Paisley Grammar saw itself as a step above other local authority selective schools, effectively part of the private sector.

We visited the Citizens Theatre regularly with school discount cards. With minimal teacher support, we ran the debating society and school magazine, spoke forcefully and wrote clearly. Musical and drama productions, the folk club, sport and trips gave us cultural breadth, intellectual rigour and personal independence.

There was mentoring before the word was invented: as chairman of the Junior Debating Society, I was supported by one Andrew Neil, of the Senior Debating Society, and shown the ropes in a gentle and kindly manner that belies his mature public persona. Working class laddies arrived not knowing what university was, but knew by the end of S2 that they were heading there.

There was inspirational teaching. Rebellion was tolerated: CND badges worn on Armistice Day, the formation of a school students’ union. The motto, Disce puer, aut abi, (Work boy, or get out!) reinforced our Presbyterian disposition: no bad thing, I hasten to add.

There were also negative aspects. I had always been aware of the social divisions in Paisley and the grammar school both reflected and reinforced these. I had not realised until the reunion in how elitist a fashion we were segregated within school. In the top stream, studying Latin as well as French, you barely mixed with the second stream and never, except perhaps on the rugby field, with the lower streams. There was also the get-out-of-jail-free card: attendance at Paisley Grammar Primary gave automatic entrance to the secondary, even to those who failed the quali. So much for meritocracy.

Boys’ sport was not merely centred on rugby, but the disdain for football and all who played it was expressed openly. The schools against which we played were also rugby-only, reinforcing the exclusiveness and the separation from the real world around us.

There was snobbery. At the end of fourth year, I told the principal teacher of PE that I would not be playing rugby. At first he was sympathetic. After I explained that it was because I had a Saturday job, his last words were: “Paisley Grammar pupils do not require to work.” He never spoke to me again.

Leadership was developed among young people, but based on the understanding that schools such as ours produced leaders and other schools produced the led. Finally, if there were inspiring teachers, there were also the incompetent (several of them former pupils) who survived to pension by virtue of conformist, intelligent pupils; there was one who, today, would be struck off the register for inappropriate behaviour.

The comprehensive system excised much of that snobbery from state schools. Those of us committed to comprehensive schooling also have to maintain the best values of the old system - cultural breadth, intellectual rigour, personal independence and hard work. That challenge is even more acute when A Curriculum for Excellence (horrific title, superb intentions) has the potential to dilute content in the laudable pursuit of strengthening engagement.

Alex Wood is headteacher of Wester Hailes Education Centre, Edinburgh.