How did you get involved in "Sweet Sixteen"?
I was in school one day and my teacher came over to a couple of us in the canteen and said that he'd set up film auditions but nobody had turned up, so could we turn up so he wouldn't look stupid. So we went along. It was kind of nerve-wracking going in, cos we'd not done anything like it, but as soon as we went in we started carrying on and having a laugh.
Could you relate to your character, Liam?
There's a lot of people saying they thought I was Liam, but I'm not at all. We're totally different people. I am Greenock born and bred, where the story is set. I've been well brought up, I've always had everything provided for me, but 30 seconds down the road is where it all happens and where the film was shot. When I was young, running with a gang was a cool thing to do, that's how you get popular, that's how you get the girls. I could relate to it but it wasn't me.
It's gruelling to watch, but how was it to shoot?
I absolutely loved it. Loved it. The way they done it was brilliant. I was knackered because the hours were long but I wasn't going home thinking, "I've got to go to work in the morning", I couldn't wait to get in to see what happened next. We shot it in sequence and it was just a great way of working. I've just done a TV thing, and they shot the ending first and it just took the fun out of it.
And now you've quit professional football [Compston was in the squad at Scottish third division side Morton] to concentrate on acting...
Bit of a soft point, there... It still is kind of my dream - my dream would be to run out at Celtic Park one day - but it just doesn't seem it's gonna happen any more. It's been the hardest decision I've ever had to make in my life, but I just need to get on with it. There's no point feeling sorry for yourself.