AT HIS theatre in Scarborough the director Alan Ayckbourn is entrusting his summer season to two middle-aged novices. They’ve never written a word performed on stage. Yet they happen to be two of the most experienced comedy writers in the business, namely Marks and Gran, purveyors of hit sitcoms to television — Shine On Harvey Moon, Birds of a Feather, The New Statesman, Love Hurts and so on. The pair have no previous connection with the Stephen Joseph Theatre in Scarborough — the comedy powerhouse where Ayckbourn has been ensconced for 48 years. Ayckbourn invited them to develop a play for the theatre, and their first play is about to open in repertory with his 69th.

“They came up to Scarborough,” says Sir Alan, “booked into a hotel and we had a long, long chat. I gave them my potted playwriter’s course, which was strange for two guys who have been so phenomenally successful in their own field. I reckoned one of the pressures on situation comedy writers was the need to grab the audience quickly before they turned over. I told them the audience are reasonably captive in a theatre and you can allow things to unfold more leisurely. In fact what they’ve written is a very serious play but laced with their special brand of wit and laughter.”

Laurence Marks, 57, is a few months senior to his writing partner, Maurice Gran. They met in the Finsbury Park Company of the Jewish Boys’ Brigade in 1960. Both are Arsenal supporters and describe their working method as a mutual war of attrition. As a duo they have had 25 years of making the nation laugh. But they were delighted, Marks explains, to be given some handy hints from the master of stagecraft. “One of the first things Alan said was: ‘There is nothing I am able to teach you about comedy, there is nothing I can teach you about character. What I can teach you is how to get the buggers on and off the stage’.”

Marks and Gran have never been entirely happy with the comedy-writers label. Indeed, there is plenty about their new play, Playing God — about an ageing rock star — that is deliberately unfunny. “The play starts with a man announcing he has terminal cancer, so I supposed that we might have thought the play was serious,” says Marks, who was genuinely surprised that at rehearsals people were laughing. “How are you going to make a man dying of cancer funny? Well, I suppose we liked the idea that no one is going to say ‘no’ to you when you are dying. That was our belief anyway. This man wants to arrange the lives of his wife and his best friend. You are allowed to do things when you are dying when normally you’d be told to f*** off.”

For Gran, like Marks, the play is the result of an ambition long deferred. He was smitten with the theatre as a child and insists that the overwhelming force of theatre experiences got him into the writing game. “The first joke I remember — I hugged myself and it made me want to be a comedy writer — was when I was 8. A space ship landed on the stage in the middle of Aladdin and a little green man got out with a cup of tea purely in order for Dickie Valentine to say: ‘How many times have I told you not to drink tea out of your saucer?’ ”

Marks says it was always their dream to work in theatre. As a child he was no less stage struck. “The first thing I saw that made feel this way was Forty Years On by Alan Bennett — I saw it in 1968. I sat there and it was just magic. If I was ever going to write, this would be the form I would choose. However, circumstances overtook us. We chose the genre we grew up in — TV comedy. Once we had — dare I say it — hit after hit after hit, there was no time to write for the stage. You were constantly servicing Birds of a Feather or New Statesman and then the BBC would say, ‘we’d like another series’ and it was another year gone. We never really had the chance to write plays.”

Between 1980 and 2000 the pair were running their company, Alomo Productions. In 1997, when a South Bank Show was devoted to them, they were invited to deliver the prestigious McTaggart Memorial Lecture at the Edinburgh television festival. They viciously put the boot in to John Birt and the prevailing culture at the BBC, which had by then turned the airwaves into a comedy desert. Things, they reckon, are improving now. But their move towards live theatre is less out of disillusionment with TV and more out of an interest in writing drama unfettered by a 28-minute sitcom format.

Was there also something more respectable, posher about theatre? “Posh people think it’s posher because TV has become so de-poshed,” says Gran. “I remember my father, who had three years of schooling and never read a book, enjoyed nothing as much as a good play on TV. This was in the Fifties and Sixties in the heyday of the single play. But poshness doesn’t cut much ice with me. I am much more excited by the fact that we’ll see something done twice. It ’s the difference between real ale and lager. TV is lager. Theatre is real ale. It’s a living piece of work.”

In the theatre their audience figures will decrease from umpteen million to around 400 a night, if they are lucky. “I am so cheered by the fact they’ve all paid to get in, I don’t care,” says Gran. “The most important realisation is that we are now doing what writers are supposed to be doing: that is, have an idea, write it and sell it. What they are not supposed to do is go to some fool of a TV producer with a Hoxton haircut and try to write what that person would like to write if he had your talent.”

For Marks and Gran this play isn’t a one-off. There is another play on the stocks and a tour of the stage version of their political satire The New Statesman — with its star Rik Mayall — is planned for later in the year. As for Ayckbourn, he has no plans amid all this role-swapping to go off and write sitcoms for television. “I couldn’t buckle myself down to that length,” he says. “I’d just be getting my characters on screen when the end credits would be rolling.”

• Playing God is at the Stephen Joseph Theatre, Scarborough (01723 370541), until September 30