Michael Scott's Machine Theatre Company turns 21 this year - time for a new identity, he tells Rosita Boland.

Michael Scott, artistic director of Machine Theatre Company, missed his confirmation with his classmates when he was 11. "I had a walk-on part in the Abbey's Shaughraun, which had Cyril Cusack and Donal McCann in it," he explains. "The play transferred to London, which was wonderful, but it meant I was going to miss making my confirmation in Dublin. My family were very concerned about that. But my father arranged for me to be confirmed in London - in Westminster Abbey, by Cardinal Heenan."

It was a colourful start to what turned out to be a life's career in the theatre. Machine's first play this year is Sisters, a first play by Declan Hassett, former arts editor of the Examiner. It's a one-woman show, written for Anna Manahan, who plays a dual role as two sisters, and it tours after its Cork opening.

In his office overlooking Sherrard Street, Scott is a bit like a bird, constantly flying from perch to perch. He invites admiration of his office chair: an inside-out affair of exposed springs. On it is a red plastic heart-shaped cushion, with rubber spikes. He opens and closes his laptop, explaining how the network was down the day before and the place fell apart. He's worried that the montage of images for their anniversary programme cover won't be ready in time for Sisters.

He sighs a lot, and mops his brow, in that exaggerated, drama-queen way that comics aping theatre actors sometimes do. Then the phone rings, and he's suddenly all business, clearly telling some agent how much he's prepared to pay for an actor in some future production.

"He's not worth more than that. He's not a TV name," he barks. Then the phone goes down, he mops his brow again and giggles.

Scott's company, Machine Theatre, was created in 1984. "I called it Machine Theatre because I liked the idea of something functional. The machine was the mechanism for making theatre." He likes this expression, "making theatre", and uses it often.

His first production was Songs for 1984, which he performed with his brother John in the bandstand in St Stephen's Green. Later, from 1984 to 1989, he was programme director for Dublin Theatre Festival.

"There was no theatre festival in 1984, so there was a Dublin street carnival instead," Scott explains. "All sorts of things were going on. Myself and John did a series of concerts of 1980s songs in the bandstand - Brian Eno, Bowie, that kind of thing. We were doing performance along with it. Part of the performance involved tossing a plastic baby doll in a frying-pan. We got a lot of reaction to that bit."

Memorable Machine productions over the years include Behan's The Hostage, a new translation from the Irish by Niall Tóibín and Scott, and Torchlight and Laserbeams, based on the writing of Christopher Nolan. In 2000, Machine put together an ambitious new version of the classic cycle of religious plays, The Mysteries, with playwrights, novelists and poets - including Joseph O'Connor, Brendan Kennelly, Gavin Kostick, Fergus Linehan and Nuala Ní Dhomhnaill - contributing a segment each. Fashion designer Synan O'Mahony, who did the costumes for this and other Machine productions, including the Cúchulain Cycle of plays, later became rather better-known on the pages of Hello! as the designer of Georgian Ahern's wedding dress.

Scott considers the Cúchulain Cycle - At the Hawks Well, On Baile Strand, The Only Jealousy of Emer, and the Death of Cúchulain - to have been Machine's finest achievement, artistically and critically, to date.

"I've always been interested in productions that are about engaging with man's struggle with himself. That's what Machine is really all about."

The plays were set to music, composed by Scott, and performed downstairs in the RHA, a space which they leased for years. "We had to try and find a new way in for audiences, and we tried to do that using sound. Each character, for instance, had its own motif of sound; they each had their own instrument."

Financially, their most successful show was The Matchmaker, adapted by Phyllis Ryan and starring Anna Manahan and Des Keogh.

Possibly their most ambitious set was for Carousel in the Tivoli in 1991, when they created a fairground in the theatre, offering candyfloss to the audience, and put a real carousel up on stage. When they toured The Field, they brought a rain machine with them, which they used in every country venue, no matter how small and testing the layout of the stage. "We wanted the show to look the same in Castlebar as it did in the Gaiety."

For many years, Machine had no base of its own but since 1999, the SFX on Sherrard Street - rehearsal and office space leased from MCD - has been home.

And for its anniversary year, there will be a change of company name - from Machine to City Theatre Dublin. As so many of the productions travel abroad, Scott feels it's better to have a name referring to where the theatre is based. The Machine, which was useful and functional for so long, has outlived itself.

Sisters is at the Everyman in Cork until Saturday, at Andrew's Lane, Dublin, February 9th-26th, and then tours countrywide