The Angels' Share's Paul Brannigan: 'I've been slashed, stabbed and shot at'

Tuesday 22 May was a good night for Paul Brannigan. To the soundtrack of popping flashbulbs and eager screams, he walked the red carpet at Cannes for the premiere of his first film, The Angels' Share, in which he stars as an ex-con who stages a whisky heist. Warm reviews were already flooding in; and director Ken Loach went on to become the surprise winner of the jury prize at this year's festival. Alongside his fellow actors, Brannigan flashed his thighs in a full monty of kilt, sporran, long socks and – reportedly – no pants.

But it was never going to hold a candle to the UK premiere at the Cineworld in his native Glasgow a week later. On his arm, girlfriend Sheree, 10 members of his family trailing behind and on his back, the tux his father bought for him for £325. "Not a huge amount," says Brannigan, "but for someone who's had a drug habit for 25 years, that's magnificent." Spurred on by his son's new-found success, Brannigan's father has spent the past two months clean – his first since Paul was born. His mother, too, is a heroin addict.

Cautiously nursing a beer in the hilltop villa rented by the film's distributors at Cannes, Brannigan speaks freely, almost evangelically, about his traumatic background. "It was tough growing up, and there were moments where I just wanted to crawl away and die. I slashed my wrist with a mirror after a fight with my dad and was just like: fuck it, man, fuck it. But it's not a sob story. I'm quite sensible; I don't get myself too close or let my emotions go. You can get hurt and then you feel your life is destroyed."

Dinky in the way of the big-screen star, with an easy smile and lavish eyelashes, Brannigan differs from your usual Cannes ingenue in both his talent and the depth of real-life experience, which Loach says helped secure him the role. His own dabbles with drugs – cocaine, he says, plus acid and valium – were not simply recreational. "In Glasgow, there's no work. There's no ships or houses getting built. No chance, no opportunities, no hope. And when you've no hope you can't get your motivation up, your self-confidence goes down and you turn to drink and drugs. It's a downwards spiral."

Expelled from school at 14, Brannigan was sent to prison at 16 for nearly four years after joining his uncle in a gun battle. He's still sore about the circumstances: "Listen, I've been involved in assaults and feuds, I've been slashed and stabbed and shot at, but that situation was something that could have been resolved differently had the police got involved after my auntie got stabbed in the head with a bottle."

In jail, he taught himself to read via a diet of dictionaries and Newsnight. "I didn't watch it for the politics; I'd listen to the way they speak, then find out what the fancy words mean, then put sentences together and learn to become articulate. I've always been small, and being small in Glasgow doesn't really get you a lot of places unless you're aggressive. So I learnt to try and use my mouth."

On release he was full of good intentions, but still "a bit of a lad, doing daft things". The scar on his face was the result of a fight with his brother. He lost a job at a community centre. But just as his character in the film, Robbie, calms down after the birth of his first child, likewise Brannigan re-prioritised after his son, Leon, was born three-and-a-half years ago.

He was spotted by scriptwriter Paul Laverty at the Strathclyde police's Violence Reduction Unit, where he teaches four hours of football a week (currently his only paid employment). But he was sceptical initially, skipped auditions, and it was only the pressure of repaying a Christmas loan that meant he finally responded to Laverty's rallying phonecalls. "It probably saved my life, to be honest. I'd nowhere to turn, got a kid; who knows what I'd have done for money."

The shoot itself was straightforward. Says Loach: "He had real emotional truth. He knew this part implicitly. He's also very astute. Some young actors have talent but you can't really read them. With Paul, you can, and that's quite unusual. He's very centred and focused and economical."

For Brannigan, the lucky break felt half like karma, half hard work. "Kids can't just wake up and go: I want a job. I worked hard for this. And it made me realise to myself I was important as a human being. I've got a point."

Since that shoot wrapped, he's already worked on another Scotland-set film, Jonathan Glazer's Under the Skin, in which he plays a lad out clubbing who is seduced and then – possibly – farmed for meat by Scarlett Johansson's alien-in-disguise. He'd like to pursue acting, he says, but, equally, he wants to continue with the football coaching and voluntary mentoring. "When you see the change in some of these kids, after eight weeks coming in and dressing smart, there's no better feeling than that."

He's not impressed by all aspects of showbiz. "We're in a recession, but you've got actors living in mansions worth three or four million. Sometimes I do feel disgusted by it." He's got a low tolerance for the publicity stunt, advises instead that the wealthy and out of touch "get in a cab with blacked-out windows one day and spend five minutes in a real life situation. Go to Glasgow city centre on a Friday night you have the real kids on the street with nothing to do; their mums are away on drugs. They're our future. I'm very, very proud to be a Scotsman. But my city's an absolute disaster. You're scared to make eye contact with someone in case they stab you."

Brannigan is that rare thing: the fully formed film star who has emerged from the ether, the acting novice allergic to undue attention. "Brad Pitt is just a guy to me: successful, handsome, doing really well but an equal. With me, what you see is what you get. There's no pissing about, there's no fucking around. Spend 10 days in my shoes and see how you do."