When I was a university student in Adelaide in 1972, three senior police headed out one night for what would later be described in a report to the commissioner of police as a ''high spirited frolic'': throwing people like me - ''poofs'' as we were so deridingly called - into the water at the city's riverside beat. Harmless fun, indeed.

One of three homosexuals who hit the lake that night happened to be Dr George Duncan, an erudite university law lecturer, and he drowned. There had been many other gay murders, but this was a visiting British-born academic, and Adelaide's respectable citizens were shocked.

The upshot was that three years later, under Premier Don Dunstan, South Australia became the first state in Australia to legislate for full decriminalisation of homosexuality.

I was able to play a small but important role in this change. I heard about the events of that night through my network of gay friends, and knew that police were implicated. I wrote a report, posted it off to the radical weekly Nation Review, and editor Richard Walsh bravely published it. Within days the story was picked up by the Adelaide

Advertiser, which identified the police involved as members of the SA Vice Squad who had been out drinking earlier that night.