American actor Rob Morrow talks with Dominic Cavendish
We walk through Soho to a vegetarian restaurant that Rob Morrow has nosed out during rehearsals for Birdy, his West End debut. He's looking confident, like he's on home soil. And in a sense he is: a New York actor in town to take part in an American writing triumph - the revival of Kentucky-born playwright Naomi Wallace's stage adaptation of William Wharton's Philadelphia story. "A rite of passage" is how Morrow describes it. Certainly, no mere tourist would have the confidence to wear his getup: black leather jacket and trousers, a green zip-up fleece, earrings and a bright red woolly hat.

Amazingly, Morrow is allowed to pass unhindered through the hordes. There is not a flicker of recognition from the waitress as he orders a bowl of Krishna-blessed beans and brown rice ("increasing peace of mind and a gradual diminishment of all material suffering" the menu promises). It's a strange low-key kind of celebrity he enjoys over here. To those who tune into Northern Exposure, the like-totally-surreal CBS award-winner set in the fictitious town of Cicely, Alaska, he inspires cult-follower awe. In six series (the last of which is to be screened soon on Channel 4), his character, Joel Fleischman, a neurotic New York doctor cast loose in elkland, went from being a narrative hook to star of the show. To non-NE-addicts, he is only known as a minor league Hollywood lead - notable for a handful of roles of the young, good-looking, intelligent-yet-compassionate school: Richard Goodwin, the lawyer who exposes the faulty manufacture of Fifties America's televisual dream in Robert Redford's Quiz Show; and Rick Hayes, the clemency board attorney who befriends his Death Row client, Sharon Stone, in Bruce Beresford's Last Dance. You can see why, in behind- the-scenes shots of Morrow being booked for his recent appearance on Channel 4's The Show, programme-makers were divided: host Bob Mills behaving like his No.1 fan, executive types going blank at the mention of his name.

At first, Morrow lives up to The Show's cruellest jibe that he is "Woody Allen without the comedy". The 34-year-old obsesses on the word "evolve": it's his primary ambition, he says. How do you mean? "You know, in all aspects of being a person." He has already, he explains, "evolved to a state where I will pay no attention to the critics. They are of no interest to me." A touch of Fleischman, perhaps, who has "undergone complete metamorphosis" (well, grown a beard) by the time he leaves Cicely? His description of his role in Birdy as shattered tough guy Al, who seeks out his boyhood friend - the introverted, ornithologically obsessed Birdy - in a military hospital after World War II, hops nervously from branch to branch. "The play is about being truthful to yourself, about people being people... there's a point where Al says that he left Birdy because he became too weird... damn, I lost my train of thought, that always happens... what I mean is not that it's better not to have your macho mask, but that Al finds what real power is as opposed to machismo... that is, err, I guess, the point."

You feel, though, that this earnestness has less to do with working long hours as the good doctor for four years, and more to do with dedication to his craft. The odd, symbiotic relation between the two central characters in Birdy has a psychological complexity that even critics have tied themselves up in knots trying to analyse. What matters, insists the play's director, Kevin Knight, is that the metaphorical force of the work comes out through raw, emotionally charged performances. "In the end, there might be actors who are good box-office draws, but that doesn't mean that they'll be able to deliver the goods. I had a hunch that Morrow was versatile just from watching one episode of Northern Exposure. On inquiry, I found that he had a huge amount of stage experience."

Put it this way: more than 35 productions since he quit school and his suburban home in Hartsdale at the age of 17 for the bright lights of NYC, taking an unusual route into acting by doing gofer backstage jobs. People he came across included the director Michael Bennett, who gave the world A Chorus Line and Morrow his first off-Broadway break, as well as the likes of Matthew Broderick and Nancy Travis with whom he set up the experimental ensemble Naked Angels in 1986. "It's still going strong," he says with pride.

Talking about those early days finally produces Morrow's trademark grin - eyes squinting, crow's feet turning on the charm. Comparisons with Woody Allen are suddenly odious. His "epiphany" watching Grease at the age of 15 is free of psychobabble: "I just watched John Travolta and it looked like he was having so much fun, I thought `what could be greater than to spend your day playing?'" He fills his days with playing now: writing, acting, looking for risks to take ("I was terrified of the complacency that sets in after a while," he explains when asked why he left Northern Exposure).The new challenge is film-making. He's set to direct a black comedy about a leukaemia patient's "nightmare experience of the industrial-medical complex" on the back of a silent short he made called The Silent Alarm, shot from a child's point of view and partly autobiographical.

He shies away from talking about his private life, though - "it's too complicated at the moment to discuss it" - and jokingly pushes away attempts to find points of comparison between his family and the one in Albert Brooks's new movie, Mother, in which he plays the high-flying brother of a blocked writer who moves back home to live with mom Debbie Reynolds until it clears. "It was just a really silly, fun film to do," he shrugs. "Nothing more to it." And off he heads to go teach the cast of Birdy a thing or two about baseball.

`Birdy' is at the Comedy Theatre, London, SW1, previewing from Wed, 26 Feb, opens 5 Mar (0171-369 1731); `Northern Exposure', series six starts 3 April, 10.30pm, C4; `Mother' goes on release in May


1962: Born in New York. His father is an industrial light designer, his mother a dental hygienist

1970s: `Too interested in meeting girls and drinking beer' to work hard at school. Epiphany watching `Grease'

1980s: Leaves high school for NYC, where he does odd jobs (usher, balloon bouquet delivery man, janitor) and acts as gofer for Norman Mailer and Michael Bennett, who gives him a break in `Third Street'. Flits between film (`Private Resort', 1985 with Johnny Depp), television (`Tattingers', `Fame') and numerous stage productions

1990: `Bigtime in debt', he takes the part of Dr Joel Fleischman in `Northern Exposure', for which he receives Golden Globe and Emmy Award nominations

1994 Stars in `Quiz Show'; leaves `Northern Exposure' after 101 episodes; directs short film `The Silent Alarm'

1996 Stars in `Last Dance'

1997 Leads in `Birdy' and `Mother'; directing a feature film, `Time on Fire'