JUST how macho is Gerard Butler?

Well, there's the Butler of 300, all muscle and rage, and the swaggering Butler of Law Abiding Citizen and Machine Gun Preacher. Even in his rom-coms he bleeds testosterone. Anyone would think the man was raised by wolves rather than brought up respectably in Paisley.

Yet here he is, the actor who makes King Kong look like Kermit, bouncing up and down on a chair like Tigger. What has got the man so tickled? To be revealed.

First, Butler wants to talk about Coriolanus, his new movie and the directorial debut of Ralph Fiennes. Playing the warrior Tullus Aufidius alongside Fiennes and Vanessa Redgrave, this is the lesser known, more thespian, side of Butler on display. (Earlier in his career he was also in The Cherry Orchard.)

The film brings Butler full circle. A London stage production of Shakespeare's tale of power and politics was the Scot's first gig after leaving Glasgow and a law career. A lot of rom-coms, action movies, indie dramas (Dear Frankie) and even a musical (Phantom of the Opera) have passed between the two jobs.

"It almost seems like another lifetime, like it wasn't me," the 42-year-old says of those early days. "I had moved down to London with no real reason, or not really deserving of getting into this business having not gone through drama school. Definitely it was a lucky break for me."

He said yes to Fiennes for a mixture of reasons, among them that it was one of the RSC's finest doing the asking.

"Whether I had done it or not I would have taken a hold of that compliment and run with it for a while. 'Ralph wants to work with you in a Shakespeare movie'. Incredible for me. Then I got the script and thought if Shakespeare could ever be a film this is it. It had it all, from political intrigue to intimate domestic moments, from rivalry to action sequences, all the complexities of every kind of relationship."

If the first Coriolanus turned him from a wannabe actor to a contender, one senses he's hoping this second production will work another transformation in how he is seen. When I ask if he regards Coriolanus as a chance to show his acting chops, he says: "I'd probably be lying if I said no, I don't care about that."

Here's the thing about Butler. His films generate serious financial heat – Law Abiding Citizen grossed £81 million worldwide, The Bounty Hunter, £87m – yet the critical reaction towards him can be icy. Especially when he makes a rom-com. "Here is a film with no need to exist," was one of the kinder things said of The Bounty Hunter.

Does that bother him? "It's a bit of a shame because, having done both, it can often be way easier to make a kitchen sink drama, way easier to get away with that and just sit on the tragedy. It can often require a lot less talent than to pull off a comedy that also has to have those [emotions]. Some of the movies I look at now that get good reviews, I've never been so bored in my life."

While he hopes Coriolanus might make some look at him differently, he doesn't want to distance himself from his past films. "The fact is, one of the reasons they can ask me to do a film like this is because you make your name cutting your teeth in all sorts of movies. There was incredible value for me in making The Ugly Truth or PS I Love You." Ultimately, he says, people will see you as they wish. "I can't get too caught up in that."

On to happier matters than rom-com reviews. Matters such as the Celtic Legends versus Manchester United Legends, the charity match played in Glasgow last summer to raise money for Oxfam's East Africa famine appeal. To say Butler looked pleased to be sharing a pitch with the likes of Henrik Larsson and Neil Lennon would be like saying the sun can be a tad warm.

Enjoy it much? The bouncing on the chair starts here. "Totally," he says with a lug-to-lug grin. He looks across at the Coriolanus poster and remembers he's supposed to be puffing the film rather than talking fitba. "So funny," he laughs. "You can take the boy out of Glasgow ..."

He flew in from Los Angeles for the match and straight back again. "It was probably the highlight of my career. Back home at Christmas, talking about it with my mum, even she said that. She's been to Hollywood premieres with me and she said it doesn't get better than that moment. 'Just to see you walk on at Parkhead.' My stepfather is a Rangers fan so it's been an infinite source of entertainment for him to have to deal with that."

When he's about to meet his maker he'd name the Legends game as one of the top three experiences in his life. So, if he had to choose between winning an Oscar, or scoring the winning goal against Rangers? "Scoring a winning goal against Rangers!"

He nearly did meet his maker before Christmas. While filming his new movie, the surfing tale Of Men and Mavericks, he was pulled under by a series of giant waves. At one point, exhausted and battered, he thought he wasn't going to make it.

"It's a very scary place. Surfers always tell you how lonely it feels when you are under that water, deep, dark. You think all I can do is not panic. If I panic I know I'm dead."

Panic was the least of it when news reached his fans. As a look at their internet sites shows, Butler enjoys a level of attention that goes beyond devotion.

"It's incredible to know you have people who care about you and are passionate about you. It's a lovely place to be, to have that other family, they want to know who's he dating, is he all right, it's nice to know they're there." (He is dating "a little bit" but won't say any more.)

The fans, he says, have even been a stabilising force on him. That, and growing older. "I lived a lot of my life where I would get into a lot of trouble when I was younger and would think, well, it's just me. You would justify your stupidity by saying, I'm only hurting myself. Then you realise no, maybe you are hurting a few more people if you get too irresponsible."

Ah, the younger, wilder, less responsible Mr Butler, the one who gave up the law to become an actor. Has there ever been a moment when he regretted divorcing himself from such a safe job?

"In 14 years of acting I don't think that thought has ever once crossed my mind. Even when I was under that wave," he laughs. "I say that jokingly, but I had my moment, I have no regrets about doing that." Scottish law is better off without him being involved, he says. "And I'm way better off doing what I'm doing."

Or as the dude from Stratford would put it, to thine own self be true.

Coriolanus is in cinemas from January 20.