Where Adrian Dunbar is concerned, the lines dividing fiction and fact refuse to sit still. It’s something he’s got used to. It’s not, however, something he’s best pleased about. That “he’s got a temper on him”, as his close friend Neil Morrissey once revealed, isn’t evident when we meet in the Riverside Studios in West London, where Dunbar is co-directing and starring in a new play about the radical Irish playwright Brendan Behan.

He does have an impassioned word or two to air about Scottish devolution, the “ludicrousness” of monarchy, and the ossification of English culture. But the only time he gets demonstrably annoyed is when I suggest that he might share personal territory with the subject of his latest venture, Brendan at the Chelsea, written by the author’s niece, Janet Behan. Like Dunbar, Behan was a self-educated, working-class Irish catholic, who believed in a united Ireland. Both men also had a predilection for alcohol that they tried to kick (Behan described himself as “a drinker with a writing problem”). Dunbar succeeded where Behan did not. In 1964, at 41, the internationally fêted author of The Quare Fellow, The Hostage and Borstal Boy was dead, having collapsed in a bar in his native Dublin. The play follows Behan to New York where, in 1963, he holed up in the infamous Chelsea Hotel in Manhattan to try to recover his capacity for writing, love and life.

“I was nothing like as bad as Brendan,” bristles Dunbar. “Alcohol was a great friend of mine for a while, but the amity went sour. Eventually the penny dropped; I thought, I just don’t like who I’m becoming. Once I’d decided to stop, I just did. No going back.”

That was ten years ago, and what drew Dunbar to Behan was the way that the genius of one of Ireland’s most explosive writers has been subsumed by his “disease”. “It’sgrossly misunderstood, and I wanted to look at that. And also at his sexuality. A lot of people just couldn’t sit with the idea that this big, roistering radical was a bisexual.”

Dunbar was also fascinated by the idea of entrapment in the play. “There was always some hack following Brendan around, lacing his drinks when he was trying to stay sober. They knew they didn’t have a story unless he was being arrested, wrecking the place, making a scene. People didn’t want to read about the sober Brendan, just like they don’t want the sober Shane MacGowan, or the sober Pete Doherty. Parade Oliver Reed or George Best on telly, completely pissed, and everybody laughs their heads off.

“But I think, actually, the man is dying. What is it that you’re laughing at? Can you not,” he asks, jabbing a finger on the table, “for just one moment, imagine what that feels like?”

Dunbar verifiably can, but therein lies the crucial difference betweenhim and Behan. He got close enough to imagine alcoholism, but not so close as to get burnt by it. Just as, growing up the eldest of seven children in a tight-knit Catholic family in Northern Ireland, he knew the ugly face of sectarianism intimately, but was never embroiled in it. Unlike Behan, he learnt, without having to fight to discover it, that “nationalism is a pretty leaky ship” of a concept.

Leaving school at 17, Dunbar took a job in an abattoir in Enniskillen, an experience he hated. By night, he played bass for the Elvis impersonator Frank Chisum, until his cousin asked him to help out with the lights for a local amateur dramatics society. For one production they were a man short, so Dunbar stepped in. The artist Janet Pierce spotted him, and arranged an audition at the Guildhall School of Speech and Drama. Getting in, Dunbar says, “was the break of my life”. He moved to London in 1980 and has remained based there since, living in CrouchEnd with his wife of 23 years, the actress Anna Nygh, and children Ted, 27, and Madeleine, 20.

Dunbar landed a string of stage parts in the early 1980s: King Lear under Max Stafford-Clark, the Bond season at the Royal Court, Ghosts in the West End. But it was his film work that earned him fame. My Left Foot, Jim Sheridan’s screen adaptation of Christy Brown’s autobiography, garnered international acclaim in 1989. Hear My Song followed, a triumphal feature about the Irish tenor Josef Locke, then came The Crying Game in 1992. Neil Jordan’s era-defining, elegiac examination of national and sexual identity set against the backdrop of the Troubles saw Dunbar head up a vengeful IRA unit as Maguire.

“The TV began to take over after that,” he says. “Everybody was fascinated by Northern Ireland so there was a lot of work, but it began to feel dodgy, always playing bent Irishmen. And I was probably drinking a bit much. Come 40, I felt I had to reassess the whole lot. Go right back to basics.”

He gave up alcohol, vowed never to spend another year without working in theatre, and only to do projects that really engaged him. “I didn’t train to do film,” he says. “I didn’t train for TV. I trained for theatre.That’s where you build something real, something alive.”

He now divides his time between London and Co Leitrim, and if he’s less regularly to be seen on prime-time television, Dunbar declares himself a happier man for it. Appearing in Boeing Boeing, Matthew Warchus’s acclaimed production of Marc Camoletti’s boisterous French farce in the West End last year was, he says, “one of the most scary, satisfying things I’ve ever done. Theatre acting is where I really get my rocks off.”

Brendan Behan’s work was drawn directly from his life experiences, of the IRA in the 1930s, of time spent in prison, of his impoverished Dublin childhood. Adrian Dunbar’s is, he says, the opposite. “For me, acting is not about remembering things that you have experienced. It’s about forgetting yourself. I’ve never been the characters I’ve played, and I hope that’s more true today than ever. Because the better you get as an actor, the less of you is visible.”

Brendan at the Chelsea, Riverside Studios, London W1 (www.brendanatthechelsea.com 020-8237 1111), from Tues

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