In 1998, a young Scottish actor, finding himself in America, talked his way into a film audition. Despite his acting experience back home, the American accent proved too much for him, and he walked away, disconsolate. “I had no idea what I was doing,” says Gerard Butler. “It was probably the worst audition I’d ever given, and in those moments you think, oh well, that’s it – obviously I’m never going to be able to do this, I’m never going to be able to act with an accent...

“You have two choices – to resign yourself to that, or to say I’m really going to give it a try. I hated that feeling of knowing I walked out of there and thinking I wasn’t good enough or couldn’t get it together. But there was a possibility that that could happen – to imagine the feeling of going into an audition and thinking that you have really impressed the pants off people, in another accent, and you could walk into a role and be able to pull that off.”

Eleven years later, his Scottish capacity for self-doubt long overcome, the Paisley-born actor is thriving. We meet when he returns briefly to Glasgow for the premiere of his latest film, Law Abiding Citizen, and if he looks slightly fatigued – he woke up this morning with what seems to be some grit in his eye (“must be stress”) – it is because the last few days have been hectic. He celebrated his 40th birthday, partied with family and friends, made his debut on Jonathan Ross’s chat-show, and today, at One Devonshire Gardens, is glad-handing the press for the new film.

In Hollywood, Butler has done action-adventure and rom-coms: the CGI-laden Sparta epic 300, which grossed an estimated $457 million; Gamer, alongside Michael C Hall; The Ugly Truth opposite Katherine Heigl; P.S. I Love You with Hilary Swank and he has just voiced a part for a DreamWorks animated extravaganza, How to Train Your Dragon. In his personal life he has, almost by default, been associated with a procession of high-profile actresses. His large duplex apartment in New York, resplendent in dark wood and chandeliers, has a first floor that “feels like a room in a castle”, according to the New Yorker magazine.

But, like many actors before him, Butler is intent on taking on more challenging roles. At 40, now is the time. In Law Abiding Citizen, which he also co-produced, he plays a man provoked to Jacobean revenge against the killers of his wife and daughter, and against the legal system which he believes let him down. Jamie Foxx, an Oscar winner for Ray, is the quietly tenacious prosecutor who comes up against him. Audiences have been known to flinch during one scene, in which Butler’s character, Clyde Shelton, tortures one of the killers to death.

“At times this movie can be brutal and, definitely, it’s slightly challenging on the nerves,” he says. “The torture scene was something that a lot of thought went into: ‘how much you can get away with before the ratings board shut you down?’, which they did on a couple of occasions. There were certain things we had to pull back on. There’s something about that scene which is so cathartic for me as a character but also for the audience, because they’re very invested in him by that point. Despite the fact that you’re horrified by what you’re seeing, you’re loving it as well.”

It’s a sign of how much Butler has come on as an actor that he is capable, in such a role, of holding on to the audience’s sympathy for a surprisingly long time. “What we played with a lot was ... bringing back his humanity,” he says. “That can be done just with little shots, to show that he’s not a monster, not just evil, that he’s coming from a place of pain and loss.” There is, he concedes, a moment when the film “goes into entertainment, becomes more popcorn, when this guy brings the city to its knees and it’s no longer quite believable.”

The film, which was shot in Philadelphia, was co-produced by Evil Twins, which Butler formed with his longtime manager, Alan Siegel.

“It’s a double-edged sword,” he says of the dual burden this placed on him. “Definitely, I felt like I had more power in the process. People had to listen to you because now you’re producer and actor. When you’re the lead actor or a co-star in a movie, you have a lot of say and you realise you don’t have to throw your weight about as much, that people want to keep you happy. They know you didn’t get there for no reason, that you have some taste, a relative amount of intelligence, an understanding.

“But when you’re coming in as a producer, especially at my part, which was more from the creative side, then I had a lot of say there as well. But then there’s the added pressure. You’re trying to focus on the role but you’re also working on any production problems or script issues. This was not the most problem-free of productions, a lot of which were for good reasons. Sometimes, if you’re trying to pull off a movie with a major conceit or that is trying to walk a fine line, you’re in between making it a great movie or a piece of s***. We were always fighting to make it a great movie.”

Since then, Butler has completed his role in The Bounty, in which he plays a bounty hunter who discovers his wife (Jennifer Aniston) is his next target and for which he spent weeks honing a New York accent. Evil Twins, meantime, is developing, in conjunction with James Cameron’s production company, the New Mexico-set Hanging Tale. A second project, Slide, sees a former Major League baseball player returning home to his estranged wife and son and becoming coach to a kids’ baseball team. “It’s like a cross between Dear Frankie and Shampoo,” Butler laughs.

He only smiles wanly, however, when the on-off Robert Burns project (scripted by Rob Roy’s Alan Sharp) is mentioned. “There have always been issues with getting it just right. It’s not an easy thing to pull off. If it had been, it would have been made a long time ago. We’ve never been in a situation where we’ve had 100% financial backing. It feels like it needs to be jazzed up a little. It was getting a little too bogged down in the heaviness and darkness of his life.”

Speaking of British films, does he have any view on the state of the domestic industry, and on Robert Carlyle’s call for cinema chains to have dedicated British screens? “There is generally a problem in the film industry all over the world. There’s not exactly a huge amount of movies being made in America either. But when I come back here and speak to people, it seems that the situation is particularly dire. I don’t have any specific answers for that, to be honest.”

He says that, like mastering accents, acting itself becomes easier, the more he does it. “The process becomes easier, because it makes sense. I remember when I would start in a restaurant when I was a law student. The first couple of days were a nightmare, everything took so much effort and thought, and you hadn’t learnt things yet. But two weeks into the job, you think, why was I ever worried? It’s a piece of cake.

“It’s the same with acting. The first time I went in front of a camera, I had no idea what I was doing. It took a lot of energy to do the minimum of things, whereas now it becomes easier and easier – although the roles you take on become more challenging, and that’s what I keep trying to do; to challenge myself more, the more confident I feel in the business.”

Before heading back into his red carpet lifestyle, Butler just has time to recall The Match, Mick Davis’s Scots-set football film of 10 years ago.

“I really wanted to do it but Max Beesley got it. I was heartbroken, gutted. But then I tried to look at it another way and it really helped.

“I thought, you know what? Good for him, because there’s a guy who’s English and managed to land a role in a Scottish accent, which is not easy at all.

“It was a lesson to me: if I want to be landing these roles and pulling them off, I have to make these leaps and go for it. And maybe one day I’ll be that guy. There’ll be somebody else who could have played the role, but I’d put in the work.” He has told Beesley as much, a gesture his friend appreciates. “There’s so much envy and jealousy in this business, and I know it just eats you up. You do a lot better when you just support people.”