It might be considered bad luck to say Macbeth out loud but James McAvoy can't be doing with any of that superstitious bunkum.

“We say Macbeth in the theatre,” says McAvoy, who plays the Scottish lord in the current West End production of Shakespeare’s tragedy.

“It’s about a man who disdains his fortune and says, ‘Damn you fate, I’m not going to die today’, and so from that moment on, he’s sort of outside of fate.

“You feel like you can’t play him unless you go, ‘C’mon, Macbeth’!” explains the proud Glaswegian, littering his sentences with swear words and throwing in a double-finger salute for good measure.

Physically, it’s the most demanding role the 33-year-old has ever undertaken, and this is the man who dodged bullets with Angelina Jolie in the action-packed Wanted and experienced the horror of the trenches in the Second World War epic Atonement.

“We’ve got cuts and bruises all over and were down the physio a couple of times a week. We’re like an army that are struggling to get through it at the moment,” says a bearded McAvoy, dressed in combat trousers and a blue T-shirt, revealing bruises on his arms.

He’s also promoting his new movie Welcome To The Punch, a slick cops and robbers-style action thriller shot in the City of London.

Surely he learned a thing or two about multi-tasking from Danny Boyle (who directed the upcoming movie Trance, also starring McAvoy, while also helming the epic Olympic opening ceremony)?

“Yeah, but the thing about Danny is he’s got a sort of advantage over mere mortals in that he’s got a nuclear power station in his belly that fuels him 24/7 and he can go and go,” says the actor, laughing.

McAvoy eschews the limelight when he’s not promoting his latest project. “It’s important for me to disappear, so audiences don’t get sick of you,” he says.

He’s also “a wee bit picky”, admitting with a smile: “I think I drive my agents nuts sometimes.”

That would explain why Eran Creevy, the director of Welcome To The Punch, has remarked how nervous he was on approaching McAvoy to play police detective Max Lewinsky.

Does it feel strange to have that sort of impact? “It makes me feel powerful!” jokes McAvoy. “No, it does make me feel funny actually because I don’t want anyone feeling nervous and there’s no reason to.

“But also, Creevy’s nervous because he needs to get somebody with a certain level of profile to get his movie funded, so all these meetings he goes into like that are make or break.”

It’s rare for a movie to be given the green light to shoot in the UK’s banking epicentre – even Brad Pitt was turned down for his new film World War Z.

But Creevy – who had only made one, albeit critically-acclaimed, movie called Shifty prior to Welcome To The Punch – has contacts in the City.

The result is a British film that looks unlike any other, which was one of the draws for McAvoy.

“I think we do great gritty British drama but I really responded to the fact that this director, this particular script, these particularly characters, seemed like something out of a Hong Kong action movie,” says the actor.

“It’s a lot slicker and sharper and a lot more beautiful, dare I say it, than the usual geezer street gangster kind of thing.”

Born in Port Glasgow, McAvoy spent a lot of his childhood living with his grandparents.

He’s spoken in the past of having once toyed with the idea of joining the Catholic priesthood, but found his interest lay elsewhere after making his acting debut in 1995’s The Near Room.

After graduating from The Royal Scottish Academy of Music and Drama in 2000, he appeared on stage where he caught the attention of directors Joe Wright (who later cast him in Atonement) and starred in Steven Spielberg’s television series Band Of Brothers.

But his big break was the Bafta-winning TV series Shameless, which McAvoy left in 2005.

It’s also where he met his wife. “Yes, and I met my missus, Mrs McDuff,” he says, smiling at the mention of the actress Anne-Marie Duff, who he married in 2006. The pair now have a two-year-old son, Brendan.

Aside from Atonement, which earned him Golden Globe and Bafta nominations, other career highlights include The Chronicles Of Narnia: The Lion, The Witch And The Wardrobe, The Last King Of Scotland and X-Men: First Class, a prequel to the phenomenally successful X-Men films. As soon as he finishes his stint as Macbeth he’ll reunite with the X-Men cast to shoot the follow-up, X-Men: Days Of Future Past in Montreal.

He’s also looking forward to returning to the character of Charles Xavier, the young Professor X played by Patrick Stewart in the earlier X-Men films. “He was a cad, almost a playboy, and I loved doing that because it kind of redefined him.”

Filming is likely to take him through to October, then he and the family will “take a wee holiday”.

“I’ve been very lucky, as it’s been a strong year in terms of different types of roles and I’d quite like that to continue,” says McAvoy.

But while it’s “fairly full on” at the moment, he jokes: “I promise I’ll disappear again.”