David Thewlis - The punk who got Naked to become an acting wizard

In person, David Thewlis doesn't look like an actor. Over six feet two inches tall, slightly dishevelled, or, as he puts it, "scruffy", he usually goes unshaven, has a penchant for open-necked shirts, black jeans and work boots, and is more reminiscent of a roll-up-smoking Northern sculptor than one of the UK's finest and most versatile thespians.

He has played, among many others, a sexual predator who pimps teenage boys, a concentration-camp commandant, a Knights Hospitaller, and a half-blood wizard in a string of Harry Potters. For his latest film, Mr Nice, directed by Bernard "Ivansxtc" Rose, he adds yet another unforgettable performance to his body of work, as Jim "just call me the Shamrock Pimpernel" McCann – a psychopathic renegade IRA fixer. The film, based on Howard Marks's bestselling memoirs, follows the erstwhile contrabandist, Marks, played by Rhys Ifans, from his humble beginnings in South Wales, onto Oxford where he studied science and physics, to his almost accidental rise from recreational drug-user to one of the world's biggest smugglers. Throughout the picture, while Marks is the calm voice of reason, McCann is the rabid terrier running around his derelict hideout up to his knees in mud and manure, frothing at the mouth like a man possessed.

"It was a great part to play because I could just let go and deliver a no-holds-barred performance," chuckles the loquacious Thewlis. "I saw the film recently and I'm so proud to be a part of it. It was great working with Rhys, who is one of the funniest men you will ever meet and someone the public always mistake me for and vice versa. He gets, "I saw you in Naked", and I get, "you were great in Notting Hill", so maybe if they now see us together on screen at the same time the world can tell us apart."

Thewlis was born in Blackpool on the 20 March 1963. His parents owned a wallpaper shop that became a toy-shop in the summer. As a teenager, he fronted a punk band that played the clubs and pubs of Lancashire. "We were called Door66, which is an absolutely rubbish name," he laughs. "I used to think we were good until someone sent me a DVD of us playing, and I thought, "it's a good job I gave it up to become and actor". I'd spent my whole life thinking we were really good, and now I know we were terrible "

Yet, in a round-about way, it was the band that prompted Thewlis to tread the boards. He and his fellow band members enrolled at Guildhall School of Music and Drama, purely as means to get to London and further their musical career.

"Soon after we got to London the band fell apart," he explains. " I was then told I was a good actor and I started enjoying it. But I hadn't planned anything. It was only during the last year that I thought it might be an option, but it still took a few years after that for me to take it seriously."

Throughout the Eighties the actor busied himself with TV roles, beginning with Only Fools and Horses. He eventually landed the role of Clive in Mike Leigh's TV short, The Short and Curlies. " I owe it all to Mike," he testifies. " He makes you a better actor because of the spontaneity and his way of working. Suddenly what I was doing made sense. He's a wonderful director for actors."

What followed was the part of Jane Horrocks's lover in Leigh's Life is Sweet, and that led to his first starring role, as Johnny, the often-homeless, at times philosophical, misfit in the director's much-lauded Naked. The role won Thewlis the utterly deserved Best Actor Award at Cannes in 1993, plus a handful of critics'-circle awards.

"The making of Naked was an absolutely phenomenal, mind-bending experience," remembers Thewlis. "That film was life-changing and put my career onto a whole different level."

Subsequently, a barrage of Hollywood scripts landed on his doormat – some of which tested his talent, while others did not. He starred with Leonardo DiCaprio in Total Eclipse, alongside Val Kilmer and Marlon Brando in The Island of Dr Moreau, and then, in 1997 played Peter Aufschnaiter opposite Brad Pitt in Jean-Jacques Annaud's Seven Years in Tibet.

The latter entailed travelling to the Andes, Italy, Austria, Argentina, British Colombia and the USA for months on end, and sharing bunk beds with Pitt. "He wouldn't take the top one because he was scared of heights," attests Thewlis. "So I told him to get used to it because we were about to be taught how to climb massive mountains."

He pauses for a moment's consideration. " But it was a long, long shoot and looking only at ice for six weeks drives you crazy, and there were no trailers or anything like that. I used to get a shovel and dig a hole and climb in it to keep warm in between takes. They'd say, 'where's Thewlis?' and I'd be in a hole somewhere. I don't know how people go mountaineering, I really don't."

In 2003 he wrote, directed, and starred in the endearing Cheeky, stole the show in Harry Potter and the Prisoner of Azkaban, and distinguished himself in Kingdom of Heaven.

In 2001, he embarked on a relationship with actress Anna Friel, with whom he had a baby girl. He joyfully admits that both Friel and their daughter have added a new meaning to his life. But isn't it difficult maintaining a relationship when the two of them are away so often?

"It's certainly not easy having to spend a lot of time apart, and having a five-year-old child who's got to be at school," he replies. "So we need to learn how to organise our time really well because for months we will be in two different countries. But then just think about poor people in war. The film I'm shooting now is about the First World War and it makes me think that often people never returned." The film in question is War Horse, directed by Steven Spielberg, in which Thewlis has a starring role.

"I had to ring my mum from the set to tell I was there with Spielberg," coughs the actor. " It's such a privilege to work with someone who was part of my growing up. I was obsessed with Jaws and graffitied it on my school bag, and I've seen every film he's made So its astonishing to be in his company."

With a well-received novel, The Late Hector Kipling, under his belt, two Harry Potters coming soon and a juicy part in London Boulevard, directed by Kingdom of Heaven writer Bill Monahan, due for release in November, it seems that Thewlis is doing very nicely.

"I keep myself content by doing lots of different stuff and make sure that my next role is completely different to the last," he stresses. " I just enjoy the versatility of it, the challenge of doing lots of different things. It keeps the job interesting."

'Mr Nice' opens nationwide on 8 October