There’s no mistaking Richard Wilson. Even if you didn’t recognise that sexy Greenock growl you couldn’t fail to spot the imposing figure of Victor Meldrew in the doorway.

Wilson is famous for his small-screen role but he’s in Edinburgh in his behind-the-scenes capacity as a fringe theatre director, a career he has sustained even while mainstream audiences have been lapping him up on the telly.

“I like to do both,” he says. “I’ve got more control over my life now because I can choose to direct and I don’t have to worry about money.”

The two images you have of Wilson couldn’t be further apart. On the one hand there is Meldrew, the grumpy, cloth-capped pensioner railing at what the world is coming to. On the other there is the sharp-thinking theatrical animal, one of the foremost directors of new writing in the UK with a career that embraces the Manchester Royal Exchange, London’s Royal Court and, last month, the Music Box theatre on Broadway in New York with his production of Primo starring Antony Sher.

In the 1960s he played Vladimir in Waiting for Godot and the title role in Uncle Vanya at the Traverse. Now he’s a visiting professor of drama at the University of Glasgow, where he was also rector from 1996-99. This man has one foot in the theatre, not one in the grave.

By staying in the vigorous areas of live performance, he believes he can stave off the Meldrew-like tendencies that afflict the elderly.

“Doing new writing means I keep in touch with what’s going on. I suppose it’s me trying to stay young. I’m 69 and the idea that some people retire at 60 just seems crazy. The danger is that if you stop, you ossify.

“My brain is not as agile as it used to be, but I love the challenge.”

One such new area is the Fife drug-running world that is the backdrop to East Coast Chicken Supper, the debut of 34-year-old Kirkcaldy writer Martin J Taylor. The play is about two small-town drug dealers perplexed by the year-long absence of their partner in crime. When he returns, they have a lot of catching up to do.

“What’s fascinating is that these are three drug dealers who are clearly very bright men. Having been dealt a different set of cards they could have been physicists or writers. Their language is extraordinary,” says Wilson.

As a director he’ll consider anything as long as it fulfils his criterion of being good writing. “I do new plays because I think theatre should be about the society we live in,” he says. “I don’t have the intellectual nous to direct classics.”

One reason he was drawn to East Coast Chicken Supper was the vibrancy of Taylor’s Scottish dialogue. “Martin’s rhythms are very important,” he says. “I just relish reading those Scottish voices. Their language is enriched by the fact that they’re working class and they swear a lot. It’s intrinsic in his writing, which would horrify a lot of people, but I find it very rich.”

The kind of people who would be horrified make up the core of his television audience. It is part of a balancing act between being a credible director of challenging theatre and that nice man off the telly.

He recalls with some glee the debut production of Iain Heggie’s A Wholly Healthy Glasgow, which he directed in Manchester in 1987. “It was very brave of the Royal Exchange to do it, because it was a Scottish patois,” he chuckles. “The language was horrific and something like 40 people walked out in the first five minutes.”

He defends the use of such language because “that’s the way these people speak” and says audiences have rarely had their illusions shattered about him. “Nobody has ever come up to me and said, ‘You should be ashamed of yourself, a man of your age’.”

Tellingly, it was an argument over ripe language that brought an end to Meldrew. “With One Foot in the Grave the BBC said, ‘We want to do more but we want to cut out the swearing’. I said, ‘If we cut out the swearing, I’m not doing it’. That seemed to me to be very real, it was part of Victor’s character.”

His experience playing in such a well-written comedy series is something he still draws on in the rehearsal room. He has learnt that, however funny the finished product, making people laugh is a serious business and an unpredictable one.

“David Renwick, who wrote One Foot in the Grave, is such a brilliant writer, but the only time we laughed was when we read the script for the first time. We didn’t laugh in rehearsal too much because the pressure was too great. But you get a line and you think, ‘My gosh, that’s a beauty’, and very often the audience doesn’t find it funny. Lines you thought moderately funny, they howl. It’s the mystery of the context, of the chemistry of the actors. It always surprises you.

“I remember being in a Brian Rix play with a director called Wallace Douglas. He would say, ‘There’s a laugh there — now you speak’. I said to him that I did a bit of directing and that I realised we worked in totally opposite ways. He said, ‘Well yes, probably, Richard, but then I’ve got a swimming pool in my garden’. Touché.”

East Coast Chicken Supper, Traverse theatre, Edinburgh, August 7-28

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