As a child, Shaun Williamson used to go to school the day after a Porridge episode and recite the best lines to his friends, so you can understand why it didn't take him long to accept the role of Fletcher in the stage adaption of the classic sitcom.

Stepping into the shoes of Ronnie Barker is not an easy thing for anyone to do, but over the last few months Williamson, best known as Barry Evans in EastEnders, has been doing just that in a tour that comes to New Wimbledon Theatre next week.

Written by the same people who wrote the original series, Dick Clement and Ian Le Frenais, the play follows a similar storyline and Williamson admitted it was a dream come true to be involved.

"It's amazing that I am playing this role, you never think you would get the chance to," he says.

"I was only 10 when it came out and I loved it, it was comedy gold.

"We used to quote the lines the next day at school.

"It was brilliantly cast with Ronnie Barker and Richard Beckinsale but if the writing wasn't good then the best actors in the world were not going to make it good.

"I only took the part because I knew Dick and Ian were on board, they would not let it be anything less than good.

"Everyone thinks they have a sitcom in them but to actually sit down and write it and make it funny is a lot harder than it sounds."

Williamson, who also starred in Extras with Ricky Gervais and Stephen Merchant, says he doesn't try to impersonate Barker on stage, though some people might see a physical resemblance.

"I knew it would be useless to try and do an impersonation of him," he said.

"People want to see some familiarity though, they wouldn't be comfortable with someone doing it in a Manchester accent.

"I use my own voice but I suppose I do a bit of a physical impersonation as I am the same age as he was, I'm 15.5 stone and from the London area."

Having left EastEnders six years ago, Williamson is still stopped in the street by people calling him Barry, something he doesn't mind at all.

"That happens all the time every day, it would be weird if people stopped recognising me, " he says.

"I was in that show for nine years and got killed off in an episode watched by more than 27m people.

"I have never regretted leaving, I've never even thought about it.

"I had a wonderful time and got out at the right time and haven't stopped working since."

As for the current mystery as to who killed Archie, Williamson says he has no idea who did it but is hoping Janine, who pushed him Barry his death in 2004, takes the rap.

"I've got £8 on her in the sweepstake at my local pub and it would be justice if she did go down having got away with killing me."

Porridge, New Wimbledon Theatre, The Broadway, February 15 to 20, 7.30pm (Tues and Sat matinees 2.30pm), £10 to £24. Call 0844 871 7646 or visit ambassadortickets.com.