"I call this the f*** file," said Kenneth Tynan. He was sitting in his office at the Old Vic, going through the mail that had cascaded in after he became the first person to use the word on television. Most letters were abusive. His wife, Kathleen, picked up one: "It's my duty to let you know," it said, "that in my opinion you are a dirty dog. For God's sake, shoot yourself." But it was not all hate mail. One letter, from a Mrs Parsons, who described herself as a housewife and grandmother, said she liked "the sweet word". She thought it had a gentleness and kindness and good humour "which describes the virility of the act". Tynan was moved almost to tears and handed it to Kathleen. But she didn't really read it.

A scene very much like this no doubt occurred in Tynan's office one day in November 1965, just after he had used the F-word. However, it had been re-created one November day in 2004 at a solid Victorian house high on East Hill in Wandsworth, where the BBC were making
a one-hour television drama entitled Kenneth Tynan: In Praise Of Hardcore. It seeks to recapture, for a generation already forgetting, the precise flavour of this prodigally gifted bird of paradise who burst on the English theatre in the middle of the 20th century. It aims to conjure up for us the marvellous boy from Brum for whom fame was the strongest aphrodisiac, shock the handiest catalyst, and laughter the ultimate weapon of mass destruction. It examines Tynan's successful fight to end theatre censorship, his gritty yet fecund relationship with Laurence Olivier in the nascent years of the National Theatre, and the turbulent launch of Oh! Calcutta!, the erotic review in which Tynan had determined to explore the new liberty or licence (depending on your viewpoint) afforded by the repeal of theatre censorship in September 1968.

The film's three main characters are Olivier, Tynan and Kathleen. Olivier will be played by Julian Sands, who was not long out of drama school when Olivier died, and never saw him on the stage — though it was Olivier's account of Richard III on film that gave him the ambition to be an actor. Tynan is the challenge facing Rob Brydon, who was not born when I wrote the first full-scale profile of Kenneth in this magazine to mark his appointment as literary manager of the National Theatre in the summer of 1963. Both Sands and Brydon were therefore curious to have someone come on set to watch them at work who had been at Oxford with Tynan, spoken with him in the same union debate when Robin Day was president, and been in his house in Thurloe Square, passably re-created for the film in Wandsworth. Indeed, like most London theatre-goers of my vintage, I'd also seen Olivier often enough in person, notably paddling the stage with his splayed negro walk in his magical Othello, and wheedling, canoodling and camping his way through John Osborne's The Entertainer as the seedy Archie Rice.

Sands has worked hard to fill this gap in his experience by having long talks with the actor Alec McCowen and the director Roland Joffe, who both worked closely with Olivier, and by meeting his son, Tarquin Olivier. Sands has, moreover, had his hair cut and grown a moustache to look almost comically like Olivier. On the set that day in a smart double-breasted Savile Row suit, he seemed the epitome of Olivier off duty — in Tynan's words, like a retired major from Sunningdale.

Brydon meanwhile has studied videos of Tynan's TV appearances to recapture the flavour of his voice. This is no easy task: I described it in these pages 42 years ago as sounding as if it had been lightly smoked and bubbled through gin.

Catherine McCormack has in some ways the most delicate task of all: to re-create Kathleen Tynan, a writer at The Sunday Times until their marriage, whom Kenneth once described as one of the most beautiful women in Europe, and who was to prove too, through mountainous highs and lows, a near-ideal wife for him.

Chris Durlacher, the director and writer of the film, catches some of the exhilarating nuances of their courtship when he has Kathleen tell Tynan that he makes out he's not frightened of anything; whereas she believes he is. Tynan assents, and lists them: "buffet lunches, Tories, striped suits, Greek food and proud virgins". Now he has a question: "Tell me five things that make you feel good about yourself." She is ready for him: "I've danced with Dudley Moore. I've dined with a defrocked priest. I've translated Beowulf. I read music. My little black dress." Tynan's heard enough: "I find I like you very much. Marry me."

It was 1962 and they were both at that moment married to someone else. In January 1951, Tynan had married an American actress, Elaine Dundy, who in 1958 was to write a bestselling first novel, The Dud Avocado. It quickly became a cult book, to her husband's intense surprise. I remember Ken telling me how he'd turned the pages and registered mounting astonishment as he realised how good it was.

The marriage, though, was not such a smash hit. "Was Elaine a trial?" the critic Cyril Connolly once asked Tynan. "No, more of a jury," he replied. In 1962, months before her meeting with Tynan, Kathleen had married Oliver Gates, once described by the historian Raymond Carr as the nicest and cleverest undergraduate at Oxford. The marriage was not a success either, and she soon left to be with Ken. She married Tynan in June 1967. Marlene Dietrich was the matron of honour.

Elaine had called Tynan one of Destiny's tots. It was not a role he felt inclined to disclaim. His own advice to himself was unequivocal: "Be light, stinging, insolent and melancholy."

A notice by his desk delineated his purpose: "Rouse tempers, goad, lacerate, raise whirlwinds." It was advice he followed rigorously. He predicted that he would live only to 30. Then he would either die or kill himself. He would by that time have said all there was to say. In the upshot, he lived to 53. Like Dorothy Parker, he had burnt the candle at both ends. Like her, he knew it couldn't burn all night. And like her again, though, he could say: "But oh my foes, and oh my friends/It gives a lovely light."

Not much about Tynan's life was ordinary, and those elements that were he swiftly excised. The truth was improbable enough. He was born in 1927, the illegitimate son of a minor Midlands store tycoon, Sir Peter Peacock, and a Lancashire girl of Irish parentage whose surname was Tynan. His father had begun as a five-shilling-a-week office boy; his mother's family had been in domestic service. They met at a whist drive in Warrington, where his father was mayor, and moved to Birmingham to avoid scandal.

Tynan went to King Edward's School, Birmingham, devoured the Peter Brook productions at the Birmingham Rep, and was enthralled at Stratford by Othello, with Frederick Valk as the Moor and Donald Wolfit as Iago. "I have seen a public event," he wrote, "of enormous, constellated magnitude and radiance." James Agate, then the drama critic of this newspaper, said: "Anybody reading this in 100 years' time should know what these two actors had been like in these two roles. In other words, here is a great dramatic critic in the making."