He was the funniest man on television, a comedian of many voices and the star of Carry On films, but there was a whole lot more behind Kenneth William's nostrilled smiles.

David Benson's show, Think No Evil of Us: My Life with Kenneth Williams, uncovers the true character of Britain's most memorable comedian while revealing a bit of Williams' personality in himself.

Benson first became linked to Kenneth Williams at the age of 13 when he entered a story-writing competition on the children's Jackanory programme. To his amazement he won. The teenager dreamed of his work being read on the show by his hero, Spike Milligan, but to his bitter disappointment his story would be delivered by the campest man in Britain, Kenneth Williams.

Benson vividly remembers his horror as he watched Williams read his piece: "He read it all wrong. He did all the wrong voices for the characters. And he was very, very camp."

This was not an ideal situation for a teenage boy at a comprehensive school in Birmingham who was struggling with his own sexuality and had a "mad mother". The result? Humiliation all round as yobs taunted the young boy with very bad Kenneth Williams impressions.

The actor admitted: "At the time I was very embarrassed. Later I realised it was wonderful."

Benson was a fringe actor in Edinburgh when in 1992 people suggested he do a one-man show. He didn't have a clue what to do it about but in 1994 inspiration struck when he saw a documentary on Kenneth Williams. He immediately bought Williams' diaries, which were published in 1993, and used them to inspire his script about the British comedian.

The show looks into the life of the great comedian as a character rather than historical figure and also reflects the life of Benson himself. "There is stuff about my own childhood and other areas of my life. It involves the audience too. They have to consider their reaction to Kenneth Williams and what it was they liked about him."

The show was an instant hit at the 1996 Edinburgh Festival and went on to pick up a Fringe First Award.

So who was the real character behind Kenneth Williams' comedy?

"He was a classic, tortured comedian who was much loved by the British for his innuendo-laden, humorous voices. Behind the mask was a rather unhappy individual who didn't enjoy being a comedian. He wanted to be a serious actor but no-one would take him seriously. It is clear from his diary he was a bitter man. That is what makes his comedy so electrifying, people can sense something about his life."

The show caused some controversy in its early days when many people complained about Benson showing the comedian committing suicide. After all, suicide was a criminal offence until 1961.

Benson explained: "It is disturbing for people who have been entertained by him. They like to think of comedians as bringers of joy and happiness who enjoy what they do. When they turn out to be as depressed as everyone else it is disturbing."

But the complaints stopped and people seem to have accepted the tragic aspect of the comedian's life. Now Benson often receives letters from people who are moved after seeing the show, saying they hadn't realised why they found Williams so touching and how much they miss him.

Benson's performance has also been praised by friends and colleagues of Kenneth Williams himself, including Barbara Windsor, Nicholas Parsons, Sheila Hancock, Barry Took and Dame Maggie Smith. They say it is the most accurate portrayal of their friend they have seen.

Benson's show leaves the audience with a striking message: "It's about trying to make the best of your life. Williams didn't love himself or accept himself as he was. You can't accept love from other people until you learn to love yourself. Each person must accept his failings. Williams was always complaining about himself. He talked himself out of intimate relationships, saying no-one loved him."

The second half of the show provides an insight into David Benson's own life. He spent much of his childhood alone with his comedy records and describes himself as "a bit of a loner". Having a schizophrenic mother made him very introspective.

It is Benson's identification with Williams' problems which makes the show work so well: "There was a bit of Kenneth in me and probably in us all. We love to sit and feel sorry for ourselves. This helped me not to go the same way as he did. We have a choice: we can be a drama queen or do something else with our life. The whole play is tied up with my own journey of self-discovery. I hope the audience will identify with it and go away with something interesting. That's the whole point of theatre, as well as being entertaining."

It seems nowadays the actor cannot escape Kenneth Williams. He is set to play the part of Inspector Truscott in Loot, which (by pure coincidence, he assures me) was played "disastrously" in the original 1965 production by the man himself.

And Williams even makes an appearance in Benson's new solo show, Star Struck, which will be in the West End's during the first two weeks of January. In this fringe play about hero worship, he plays other icons he worshipped since his childhood days: Fred Astaire, Frank Sinatra, Noel Coward and Judy Garland.

"They are all at a party and turn out to be awful. It is about debunking your own hero worship and being yourself. I also perform a duet with Frankie Howerd and Kenneth Williams. I can't get rid of him he creeps into everything!"

You can see David Benson in Think No Evil of Us: My Life With Kenneth Williams, Dec 13, Croydon Clocktower, Braithwaite Hall, Katharine Street, Croydon, 8pm, 9/6, 020 8253 1030.