In the title role of Harmony Korine’s julien donkey-boy, which was shot on digital video and without a script.

As an actor, Ewen Bremner has never taken the easy option: his biog is littered with the kind of roles that would convince Mrs Worthington’s descendants she was right not to have put her daughter on the stage, let alone into the talking pictures.

Bremner was, for instance, the original Renton - the guy who stuck his head down the Worst Toilet in Scotland - in the Edinburgh Traverse stage production of Trainspotting (and the subsequent London transfer), moving over to play the hapless, incontinent Spud (more shit) in the movie version.

His big-screen debut came before that, though, when he played Archie, the manically aggressive Scottish youth David Thewlis meets on the night-time streets of London’s Soho in Mike Leigh’s Naked. More recently, he has starred in Jez Butterworth’s Mojo and Paul McGuigan’s Acid House - another couple of out-there movies.

So it’s not altogether surprising that Bremner should get this phone call from Harmony Korine in New York. Korine, to judge by his films, is the kind of guy who could only exist in New York, although his biog reveals, rather improbably, that he was born in California and partly raised in Nashville, Tennessee. Still, you end up - if you’re lucky - in the place the suits you best, and Korine ended up in New York.

Anyway, he wanted Bremner to come over and make a movie on the streets of Queens, Yonkers, Harlem and bits of New Jersey, working with hand-held digital video cameras and no script. Werner Herzog, the cult German director of the late sixties, seventies and eighties - one of Korine’s idols, as much for his uncompromising approach to film-making as for the end result (Aguirre, Wrath of God, Fitzcarraldo) - would be playing his father. Also in the cast were rising star Chloë Sevigny, who played the lead in Kids; Korine’s grandmother, Joyce; and Chrissy Kobylak, an 11-year-old blind ice-skater from San Antonio, Texas, whom Korine had spotted on tabloid TV.

Bremner knew Korine’s work - the screenplay for Kids, a film for which that lame old stand-by ‘controversial’ proved grossly inadequate, right from the moment it sent audiences reeling out of a midnight screening at Sundance; and Gummo, his directorial debut about a kid on the fringes of society, which won prizes from festivals and brickbats from the moral majority in about equal measure.

So Bremner obviously wasn’t expecting to be offered a part in a musical. But a film without a screenplay? A film which would require him to do research by working as an assistant in New York’s Wards Island Institution for the Criminally Insane and then go out on the street playing scenes against passers-by for hidden cameras? How could he say no?

But, insists Bremner: “Harmony didn’t say to me, ‘I’m making a film without a script’. He said, ‘I’m making a movie that’s going to be like nothing else.’”

And he did.