I had completely forgotten until this week that I celebrated my 16th birthday on the very day that an important influence on my young life, Radio London, went out of business. I was reminded of the station's demise by various allusions in the media to the 40th anniversary of its shut-down (a victim of the Marine Broadcasting Offences Act), which occurred on Tuesday. Many people of around my age, I feel sure, will have vivid memories of "wonderful Big L", which had the good fortune to be on air (from December 1964) at a time of unparalleled excellence in popular music.

But it is another recent anniversary that I intend to celebrate today - the 21st birthday of Headington's famous rooftop shark. Here, too, there is a broadcasting connection since, of course, its owner, Bill Heine, has gone on to become the best-known name on BBC Radio Oxford in the years since he entertained the world (literally so) with his novel artistic commission.

I feel a special affection for sculptor John Buckley's fibreglass fish - oddly, he (she?) has never acquired a nickname - since I was 'in at the birth'. Bill and John had been pals of mine for a good few years by 1986, partly in consequence of my having covered the pair's earlier artistic collaborations. These were the Al Jolson hands and Mae West lips at Bill's Penultimate Picture Palace and the naughty can-can legs at the (now sadly no more) Not the Moulin Rouge cinema opposite Bill's Headington property where the shark was later to appear.

I was one of the first to be given a clear idea of what was in the offing when Bill suggested we should lunch together to discuss a special project. Over smoked salmon and salads in the sunny garden of the Abingdon Arms, in Beckley, on Thursday, August 7, 1986, he handed me John's sketch of the work.

The official title of the sculpture given on it was Untitled: 1986. John listed its mixed-media components as "fibreglass, bricks, mortar, flowers, curtains, people."

Back at the office I showed the drawing to the picture editor and others, and explained that this was what Headington would be waking up to in 36 hours time. I had the impression that I was not taken entirely seriously.

But I have always known of Bill that he shares a characteristic with David Bowie's Queen Bitch: "If she says she can do it, then she can do it; she don't make false claims." So I was entirely confident about what I was going to find when I drove up to Headington at 6am on Saturday morning. And I found it.

During the hours of darkness, the shark had been brought by tractor and trailer from the farm near Wallingford where John had created it, lifted by cranes above the roof, and bolted by a group of off-duty firemen into a specially made slot in the slates. The final stages of its winching into place were captured by our photographer George Reszeter who raced back to the office with his prize. Now they believed me . . .

My story about the shark's sudden appearance was the splash in that day's Oxford Mail, in all the national newspapers the next day and round the world in the days thereafter. I wrote: "The sculpture is described as 'art with a bite' by its owner Mr William Heine my, weren't we formal in those days!, who is certain to face a row with planners over the weird decoration."

This turned out to be a notable understatement, for my predicted row lasted fully six years and was only finally resolved through the approval of the then Environment Secretary Michael Heseltine. (Sound man: pity about The Dome.) Fifteen years on, scaffolding cloaks the shark as John Buckley concentrates on beautifying his work with a new colour scheme. Bill tells me: "He is creating a shark for now. It is going to be really alive and in exciting colours that will make people look again at something they thought they knew well."

That must mean, I think, that we are in for another very big surprise.