That, at least, is the received wisdom. And, like much received wisdom, it is often wrong.
Screen star Iain Robertson – who returns to the Scottish stage in Donna Franceschild's Takin' Over The Asylum (a co-production between Edinburgh's Royal Lyceum and Glasgow's Citizens Theatre) – defies the pessimistic common sense. Although he made his name as a movie actor at the tender age of 15, when he starred in Gillies and Billy MacKinnon's award-winning film Small Faces, and has since played in such films as Plunkett & Macleane, The Debt Collector and Basic Instinct 2, the 31-year-old actor is often to be found treading the boards of his home country.
In 2009, Robertson, who hails from Govan, starred in the Lyceum's adaptation of James Hogg's Confessions Of A Justified Sinner. Last year he wooed critics and audiences at the Edinburgh Fringe with a brilliant solo performance in Ronan O'Donnell's Angels at the Traverse.
Nevertheless, it is perhaps appropriate that Robertson's latest Scottish stage project is the child of a screen drama. Takin' Over The Asylum is American writer Franceschild's stage adaptation of her own much-loved 1994 TV series of the same name, which starred Ken Stott (as put-upon Glasgow mental hospital DJ, Eddie) and a young David Tennant. Not only that, but Robertson acted, at the age of just 14, in the series' sequel, A Mug's Game.
So when the call came from the Lyceum offering him the role of Eddie, he accepted with enthusiasm, he tells me when we meet at the Edinburgh theatre. A great admirer of both Franceschild and, he is delighted to be working with them both again, and is particularly impressed by Franceschild's adaptation.
"Donna is phenomenal at structure," he says. "Her script feels like a play. It doesn't feel completely different [from the TV show], it's got the same soul, but it's a complete piece in and of itself. It doesn't feel like six hours of telly condensed into two hours of theatre."
Which is not to say that Robertson has been looking back at the TV series. "I haven't gone back to it recently, because I didn't want it to colour what I would be doing with it," he explains. "I must have been 13 at the time the show went out. I was getting into the business then, so I was drawn to it. I have images in my mind, but I don't have a clear memory of it. I'll probably get a hold of a copy of the show after we've finished this production. I bet I'll watch it and go, 'Oh f***! That's how I should have done it!'"
While he hasn't returned to the TV series, Robertson has talked about the play with Stott, alongside whom he acted in A Mug's Game. "Ken was very nice when I spoke with him recently," Robertson adds. "I went to see his Uncle Vanya [at the Vaudeville Theatre in London] on the infamous night of the supposed heckle by Peter Hall. Ken was very generous. It's a part that's very dear to him, and he's kind of chuffed that it's being kept in the family."
By "the family" Robertson means not just Franceschild and the actors, but a whole panoply of off-screen people who were involved in the making of Takin' Over The Asylum and A Mug's Game. Robertson and Franceschild were reminiscing about those days recently, and the actor was reeling off a list of names of people he's still in touch with, including someone called Damien – to which the writer, who'd only been half listening, responded with surprise, "Damien? Did you know that's what we called you?" Unbeknown to Robertson, ever since the days of his precocious teenage breakthrough, his nickname among the Mug's Game crowd has been that of the devil child from The Omen films...
The actor finds this story highly amusing, and it certainly does nothing to dent his admiration for Franceschild. In particular, he believes that the play, like the TV series before it, makes an important moral and political point regarding mental health. "If you break your arm, you're not defined as a guy with a broken arm", he comments. "But if you say, 'This is my friend, who has bipolar', it's a different matter. People are defined by their mental health condition. Donna has bipolar. Donna's a great writer, a mother, a friend, and many other things. It's horrible when people's identities are whittled down to the label 'a person with bipolar'."
Robertson is clearly proud to be taking the lead role in a play which manages to make such an important point while also being very funny and fabulously musical. "You go in on the first day of rehearsals and you're reminded that the piece has all this wonderful music," he says. "Then you relax a little bit and you think, 'Well, at least if I'm crap, the music might carry it a little bit.'"
Takin' Over The Asylum is at the Citizens Theatre, Glasgow, February 14-March 9, and the Royal Lyceum, Edinburgh, March 13 -April 6
Actor Iain Robertson's latest theatre project is the stage adaptation of the 1990s TV hit, Takin' Over The Asylum. Here, he talks to Mark Brown about his admiration for its writer, Donna Franceschild, the stigma of mental illness ... and how he was once nicknamed Damien after The Omen devil child