PETER Mullan is great at many things.

He's an intense, edgy screen presence in films such as My Name is Joe and Tyrannosaur, and Jane Campion's recent TV series Top of the Lake.

He is also an award-winning director, famous for his work on Orphans, NEDS and The Magdalene Sisters.

What he is not, he'd be the first to admit, is a great singer.

So he might not be the first person you would turn to when making a film version of the Proclaimers musical Sunshine On Leith.

And yet he jumped at the chance to play the father figure in the movie opposite Jane Horrocks, even though it meant crooning the Proclaimers tune, Oh Jean.

"I'm not tone deaf. That's all I'll say," he tells me, laughing, in Glasgow the morning after the Scottish premiere of the film, directed by former TV star Dexter Fletcher.

It's not what you might expect from someone many of us think of as the go-to guy for Scottish dysfunctional men.

But then again he's also appeared in Harry Potter and Steven Spielberg's War Horse.

And the simple fact is, he says, he loves musicals.

"I was brought up on musicals. I love musicals. It was what was on on Sunday afternoons," he says.

"Some of them you were more proud to admit to than others.

"I loved all the dancing ones. Gene Kelly was my hero. Jimmy Cagney was my big dancing hero.

"I always found the ones that thought they were more muscular like West Side Story were more camp in my book.

"The Jets song has me on the floor because I can't take it seriously. As much as I think it's an absolutely stunning musical - it has some of the greatest numbers ever written - some of those dance routines just drive me nuts because they are so camp.

"There's no other way to describe it. It's just camp."

Instead he'd rather watch Meet Me In St Louis or Easter Parade. And, given the chance, he'd love the chance to make something in the same vein.

"I would love to direct one. I would really love to direct one," he says. "Watching Dexter was brilliant because I learned a lot watching him work.

"I was always quite intimidated by the technology of it. But any actor - particularly of my age - their big ambition was to work on a Dennis Potter, for no other reason than because he was without doubt the greatest television writer and possibly cinematic writer of all time."

Potter, who wrote for British television between the 1960s and the 1990s (he died in 1994) famously had the actors break into song in The Singing Detective and Pennies from Heaven.

"He gave you this perfect context, this amazing character, and you get to sing as Bing Crosby," he says enviously.

Sunshine On Leith might be the nearest he gets, though. And it proved a great experience.

He was very impressed by Fletcher's shooting of the film.

"Dexter has got a great eye. Some of his cutaways are just beautiful," he says.

"He's got such a nice manner. He's a great director and you really see it on set. Everybody's really happy and enjoying their work.

"A lot of directors can't do that. They get so tied up with the pressure of things - the time factor, the science, the art, the business - so when it comes to actually dealing with people they're just duff.

"I think the great directors are always really good with people, I find anyway. They know how to create a nice party atmosphere."

He says he has been lucky enough to work with many of the greats.

"Ken Loach definitely. Mel Gibson, Danny Boyle, Mike Figgis, Jane Campion, Spielberg; they're all really good with people," he says.

"They can be tough on crews and stuff, don't get me wrong. But they've all got that one thing in common. They just inspire."

He knows what it's like to be in the director's seat himself, of course.

It's now a decade since he made his breakthrough with The Magdalene Sisters, a heartbreaking account of the treatment of women in Ireland treated likes slaves at the Magdalene laundries run by the Catholic Church.

He can't believe how much has come out in the years since. Women in both Ireland and Germany have received compensation and, just as importantly, recognition of their story.

"I'd never thought we'd get so much," he says.

HE thinks the apology given by the Taoiseach Enda Kenny is one of the greatest parliamentary speeches ever given.

"No beating around the book, he apologised unreservedly," he says.

And rightly so, he thinks: "It wasn't just the Catholic Church. It wasn't just the Protestant church. It was a society that had become toxic.

"The only grief I ever get from Magdalene is from ex-inmates saying 'You should have been harder on those nuns.

"You were way too nice.'"