A man carrying six-packs stands in an empty, obviously disused classroom. It is 11.30 on a summer's night. We are told he is 32, also that he is overweight. Clearly, he is visiting his past. When a woman enters the room, he responds not with a line of verse but somewhat more mundanely: "Oh Jaysus! Oh hello, come in, come in - you're Jimmy's wife aren't you?" The Last Apache Reunion (1993) is typical of Bernard Farrell's form of social comedy - it is constructed on the instantly recognisable world of ordinary human activity with its mistakes, regrets and moments of discovery. There are no myths, no agendas, few heroics and little poetry. It is a theatre of real life, nothing fancy, unabashedly commercial: it fills seats and Farrell lives on the royalties.

Entertainment is his priority. "I want people to enjoy themselves." But it is not all high-speed farce. A work such as Happy Birthday Dear Alice (1994), which was commissioned by Red Kettle Theatre Company, was inspired by a situation Farrell and his sisters had long dreaded - that it might become necessary for a parent to be moved to a nursing home. His new play, Kevin's Bed, commissioned by the Abbey, which opens next week, also examines the internal tensions, hopes and failures of a family sustained more by lies than the truth. "It's a memory play," he says, "and the two wedding anniversaries each stand for different things; social mores and the changes."

His characters invariably speak very quickly - the dialogue is sharp, the lines are short - and move fairly fast as well. In his plays, life tends to catch up with even the most inventive.

Farrell makes no mystery of his art, "but I do believe it is special," he says candidly. "I don't know where it comes from. I've been at parties and you know the host always has a word for everyone he doesn't know - he'll say something to the doctor, the shipping clerk, the whatever - but when it comes to a playwright, people just seem to say, "oh you write plays, do you?", and move on. It's a real conversation-stopper. But then, for all the talk about theatre it's only about 7 or 10 per cent of the population is active theatre-goers - I mean real theatre-goers." Farrell is right. Many of the people who make an occasion out of a Murphy or Friel first night might see only those plays in any given year. Real theatre-goers are far more scarce and, as Farrell stresses, "there are several different types of theatre audience".

In common with his friend Hugh Leonard, Farrell was excluded from The Field Day Anthology Of Irish Writing. "I think it was a disgrace. Not so much for myself but for Jack (Hugh Leonard): he has made a huge contribution to Irish writing. He deserves an awful lot more than he gets. As for myself, it doesn't bother me. There are many different types of plays. I don't think `popular' should automatically mean it's no good."

Farrell is adamant he has no agenda and seems an easy-going, likeable character. In person, he is very Dublin, very funny - in fact, funnier than his plays. Wondering why he ever began writing plays, he says, "I never won arguments. I'd always think of what to say afterwards when it was no use. Maybe that's what got me going?" Almost philosophical in his handling of the fact that his popularity, as much as the style of his plays, has set him outside the attention of the critical establishment, Farrell is modest but not naive, and has not forgotten the slow critical acceptance accorded to John B. Keane.

Much of what Farrell says about theatre, as well as much of what has been said about his work, could be applied to the English playwright Alan Ayckbourn. Interestingly, however, Farrell does not welcome the comparison - although he concedes that they both write about the foibles and pretensions of an easily identifiable middle class - Ayckbourn's English characters are more concerned with social climbing, while Farrell's middle-class Dubliners are usually trying to conceal their mistakes.

"I'm not mad about Ayckbourn," Farrell says. "I know he's good - but I'm wary of being compared with him. It's such an easy connection to make. I prefer Tom Stoppard. I think he started off brilliantly with Rosencrantz And Guildenstern Are Dead, Jumpers and Travesties and then went into a sort of a lull and I almost gave up on him with Hapgood - I thought that was pretty awful - but he suddenly bounced back with Arcadia, which I adored, and Indian Ink" (which is a stage adaptation of Stoppard's own radio play, In The Native State). "The last few have been great. Although he is regarded as an intellectual playwright, he's not an elitist. He'll drop everything to write a radio play. I'd regard him as a real theatre person. He's good alright."

Farrell also admires Dennis Potter. "But I like him more as a television writer. I remember watching The Singing Detective - it was so entertaining and confusing and challenging so I stuck with it and at the end everything pulled together. And then he went and wrote Black Eyes and everything that had worked in The Singing Detective failed. But at the end of his life with Cold Lazurus he produced something wonderful. I loved David Hare's Amy's View, that's wonderful - Hare is very good. I also love Alan Bennett and Simon Gray." Of Gray's An Unnatural Pursuit, he says "that should be required reading for any playwright".

Harold Pinter is his all-time theatrical hero. If there is a single theatre experience which determined Farrell's career it was a production of Pinter's The Birthday Party at the Abbey in 1976. Although it was far from the first play he had seen, it created a lasting impression.

Born in Dublin in 1941, Bernard Farrell grew up in a world in which everyone around him seemed obsessed with the movies. "I had to pretend I'd gone to the pictures, when I'd really gone to the theatre. I always been interested in it, it was always part of our lives," he says. At that moment, a soft-toy effigy of ET balanced on the radiator behind his chair catches the eye. Theatre posters featuring productions of his plays fill the walls.

Meanwhile, as if anxious to correct an impression of elitism, Farrell is qualifying his last words by describing how his family - father, mother and three children, the young Bernard the middle child between two sisters - regularly packed up a large flask of tea and sandwiches "in the old greaseproof paper, you know the stuff? Very noisy" and went by bus or train into the city, to the theatre. "My father loved O'Casey, my mother loved Shakespeare. They were both very aware of it. I'm not trying to say that my mother only liked Shakespeare - but she was great, you know. If someone said a word, any word, she'd always have a line of Shakespeare to follow it. Say you said, "mercy', she'd be off "the quality of mercy is not strained" etc. Anyhow, we were all heading off to the theatre." From his earliest years, it was always live entertainment, it was also an outing. "Exactly that. No snobbery about it, whether it was panto or a circus."

No distinctions were made, "but we knew the difference". "We'd eat the sandwiches, passing them along the row in the dark, greaseproof paper crackling, one of us protesting `I wanted ham, but I got cheese', eyes locked on the stage. And the other people would begin shushing us." Meanwhile, his mother would be busy trying to unscrew the cap of the flask quietly. "The only way to do it without making an absolute racket is to do it quickly but my mother did it so, so slowly, it was painful and of course, very loud." At the intermission, the Farrells never left their seats. "We'd stay put and our parents would ask us what we thought of the play so far, who was good, who wasn't and what did we think would happen next." If the children were unimpressed, they were not reprimanded, but were asked for reasons. "It wasn't like being cross-examined. Our opinions mattered." His Sandycove childhood was happy and he was to move back home regularly up until the age of 40. Life at Monkstown Park school seems to have been trauma-free. "I wouldn't say I was good at school," he says honestly. "It wasn't the teachers' fault, I was always more interested in other things so I wasn't the best subject to teach. Although I knew my parents made sacrifices to send me there." He mentions that he played rugby, mainly on the wing. "I was an OK runner. I liked sport but I was too lazy to train." Ambition did not feature in his life. "I had always written bits of poems and stories".

He seems surprised to be asked had he not considered university. "Going to college was just never part of my life. You left school and got a job; played football and chased girls." His attitude is unusual, particularly when so many people appear to be tormented artists. "Am I very dull?" he asks with convincing concern. "Maybe I should throw a plate or something?"

Rain is half-heartedly threatening the large housing estate in Greystones, Co Wicklow where Farrell lives. It is the first house he has owned and he has lived there since he and Gloria married 13 years ago. Although he has a new play just about to open, Farrell is more concerned about his dog's health. Cleo is a fastidious-looking little King Charles spaniel, friendly with the standard, ultra-mournful eyes of her breed. A 101 Dalmatians towel covers the cushion in her bed. "Yesterday she was really sick, she couldn't move. We thought she was going to die. Gloria took her to the vet and he said she had pneumonia with a temperature of 104. He gave her an injection and look at her, she's great. It's amazing the way they bounce back." Theatre's many devices are extremely important to Farrell, as is music. "There's always a song in my plays. Even if a person mentions they've seen one of my plays but can't remember the name, I just ask them to mention the song and I know what they're talking about."

For all he appears so relaxed and ordinary, his approach to theatre is deceptively systematic. His study is ordered and uncluttered. He takes notes all the time. Anything that could be useful, the smallest gesture, most casual comment, is recorded. "The secret is never to think about what you say," he says.

None of his characters, with the exception of Alice in Happy Birthday Dear Alice, appears to have an inner life. They invariably respond to their situations. His work is strongly situation-driven. This observation causes Farrell some concern and he points out: "I usually have my characters first and have made notes on them before I work on the plot. But I suppose you're right." He does not seem particularly convinced. Nonetheless, he soon recovers and continues: "Some of these classes you go to learn how you write a play - I think they're deadly. They make people put too much importance on a formula."

When he left school he worked for an estate agent before joining Sealink as a clerk. He remained there for "it must have been 14 or 15 years. That's when I began travelling all over. At first I went to silly places" - and he lists a number of gruesome Spanish resorts - "but then I began to go to more interesting places like Albania." Although warned in advance to wear short hair and refrain from smuggling Bibles into that determinedly communist country, Farrell was arrested and informed his recently-cut hair was not short enough. It was then cut tight to the skull.

About the same time, he and a pal had begun attending playwriting classes. His first play I Do Not Like Thee, Dr Fell was staged at the Abbey in 1979. It was one of the first plays Joe Dowling produced there. It also marked the beginning of Dowling's policy of encouraging new playwrights. Farrell was on his way and soon resigned his job. Farrell's relationship with the Abbey has always been good and he is a former writer-in-residence.

Aware that this spoof on psycho-therapy is a difficult play to do, Farrell says that "even now people write to me from abroad and say `this won't work' but Joe saw something in it and I will always be grateful to him for getting me started".

His entire career has been judged against the success of his first play. Has he come to resent it? "Not at all, I'll always be grateful to it. It's my Catch-22." That immediate success also freed him - not that Farrell appears to have been particularly unhappy at Sealink.

How did his parents respond to his success? "My father didn't live to see any of it. But he did read an early draft of Dr Fell and I remember him saying `it could work'. When the play opened in 1979, he was dead and I missed him at it." Elizabeth Farrell died five years ago. "She saw all my plays up to then and was a great support." Writing plays, he believes, should be spontaneous: Farrell does seem wary of the process being overly contrived in the early stages of conception. "The first draft has to pour out of you. It is a mess structurally. The next draft brings a structure to it. When I'm doing the first draft, I always use a stapler. At the end of the first draft I have a foolscap pad of stapled-in notes. Then from that sort of mess, the second draft becomes much more refined. It is much more presentable."

Farrell says his first drafts essentially assemble all his thoughts; this is where he "chucks them into this open space with great abandon". By the second draft a discernible script begins to emerge. Only with the third does he move on to the word processor. "The fourth tidies everything up and looks at the dramatic rise and fall of the play." Technique takes over at this stage, "And I do have a strong belief in its devices," he says, adding "the playwright must be in control of the audience".

Does he enjoy writing? Laughter. "I don't actually like writing. Writing plays is a torturous business. I mean, I put it off until I have no more excuses. But I have been lucky. I am usually writing to commission and there is a deadline. Even if there was no commission I'd still write them, though."

Life for Farrell is about normal things, such as walking the dog and going to football matches. "Writing plays is only a part of that real life. I have a normal life beyond writing plays. When I'm not writing I relax but I'm always on the lookout for ideas." No agenda drives his work, but he has a motive. "There's always a motive. It's like in the old gangster movies `do you have a motive'. Everybody has a motive."

Kevin's Bed opens at the Abbey on Wednesday, April 29th, with previews from next Thursday.