Interview: Why actor Mark Strong is an accidental anti-hero

On the morning I'm due to interview Mark Strong I receive an e-mail from his publicist politely requesting that we meet near to the actor's Queen's Park home as he doesn't want to stray too far from his new-born baby. It's disarmingly, and perhaps a little disappointingly, New-Man-like for the brooding actor who is best known for bringing the serial philanderer and wannabe rock star Tosker (in Our Friends in the North) and the East End gangster and porn king Harry Starks (in The Long Firm) to the small screen.

It's reassuring, then, that within hours he has changed his mind and is striding into the louche drawing room of the Soho Hotel, baseball cap pulled low over his eyes, a smattering of stubble darkening his face, swearing liberally about the state of the London traffic.

We are here, after all, to talk about his latest villainous incarnation in Stardust, Matthew Vaughn's surprising follow-up to his gangster debut Layer Cake. In this British take on a classic Hollywood fairy tale, Strong plays Septimus, the seventh in line to the throne of the mythical Stormhold, ruled over by an ailing King (Peter O'Toole). Ruthless and scheming, he will stop at nothing to remove his brothers (a stellar line-up of Brits including Rupert Everett and David Walliams) and find the fallen star (Claire Danes) who holds the key to the kingdom. Also chasing the star are the witch Lamia (Michelle Pfeiffer), who believes that it holds the promise of eternal youth, and the lovelorn Tristan (Charlie Cox), who wants to impress the lovely Victoria (Sienna Miller).

Strong decided to play Septimus "like a ballistic missile" – and it shows, as he smoulders his way through every scene, putting on a flowing black wig and his best evil purr, even uttering the immortal line, "All right, twinkle-toes?" to Robert De Niro's unconventional pirate.

"If you think about Shakespeare, you remember Richard III and Macbeth before you remember Ferdinand, whose role is just to fall in love and be a bit of a wimp," he says, sipping on his fresh orange juice. "I love the baddies. More important, though, is making the baddies somehow, weirdly, understood."

He's had plenty of practice lately, having made seven films in the last year. Still to come is his "horrendous" botoxed LA agent (opposite Daniel Craig's fading star in Flashbacks of a Fool), a cocaine-addicted 1930s nightclub owner (Miss Pettigrew Lives for a Day), "a cultured, charming Nazi" (Good), Archie the gangster in Guy Ritchie's RocknRolla and the violent guardian of the Queen (Emily Blunt) in The Young Victoria.

He's currently shooting Ridley Scott's new Middle Eastern epic, Body of Lies, in which he plays the smooth-talking, Savile-Row-suit-wearing head of the Jordanian Secret Service. "A fantastic wildcard," he admits. "But why play safe and think: 'well, no, unless he's white and from London and talks like me, I'm not going to do it?'" He ascribes this purple patch to his recent appearances in Syriana (playing the Iranian agent who tortures George Clooney's character) and Roman Polanski's Oliver Twist.

Until now, Strong has maintained a fairly low profile, partly, he thinks, by never wanting to play the kind of leading characters we root for and partly because he has hopped about between theatre, television and film. His first job, straight out of Bristol Old Vic drama school, was doing nine plays in nine months at the Worcester Swan Theatre. There followed a nail-biting six months when he thought he'd never work again. It turned out to be the only time the actor, now 44 years old, would find himself unemployed.

He first carved out a brilliant career in the theatre, including spells at the RSC and the National – where, along with Kate Beckinsale, Stephen Dillane and Sally Dexter, he workshopped and later starred in Closer – and in high-profile parts in The Iceman Cometh with Kevin Spacey at the Almeida, David Mamet's Speed-the-Plow in the West End and in Sam Mendes's Twelfth Night at the Donmar.

In 1996 came his big break in Our Friends in the North alongside fellow unknowns Christopher Eccleston, Gina McKee and Daniel Craig, who is now godfather to Strong's two-year-old son. Strong had no idea it would be so successful.

"And Dan didn't either. I remember walking down the street with him one day saying: 'do you think this is going to be any good?'", he says. "It was only afterwards I realised that it's a serious political look at the state of the nation for those 30 years. I think people related to it because it was a really intelligent piece of television."

It could all have turned out very differently. Marco Guiseppe Salussolia was born in 1963 in London to a teenage Austrian au pair and a second-generation Italian immigrant who walked out when he was a toddler. Far from being a precocious young performer ("Perish the thought!"), he became a tearaway and, aged six, was sent away to a school for difficult children. At boarding school in the 1970s he played bass in a "noisy punk band" called Private Party and performed in one play, Derek Benfield's farce The Post Horn Gallop. "I played a scout-master and the whole gag of that character was his knobbly knees peeking out from his shorts," he says wryly. "I only did it as a giggle really and it never made me want to do any more."

Although bilingual, he was "too lazy" to sit the exams to study German at Cambridge and instead went to read law in Munich. After a year, he missed his friends and came back to London, alighting by chance upon his English and drama course at Royal Holloway .

"On the way to G for German in the prospectus, I hit for D for drama and there was a picture of a guy in a dinner suit and a girl in a big white dress and it said 'Oberon and Titania in A Midsummer Night's Dream'. I thought they looked fabulous. It was around the time of Brideshead Revisited and everyone wanted to be fabulous."

These days, life is rather fabulous for Strong. While his career is on a comfortably upwards trajectory ("In the past, if I didn't work, I didn't eat but now I feel I can not work and I won't starve"), he's also blissfully happy at home with his partner, who works in television, and their two sons, who, along with learning lines, take up most of his free time.

"I had this extraordinarily bizarre moment when, two Fridays ago, my missus gave birth to our second child at 11am and by the same time the following day I was sitting around a table with Ridley Scott, Russell Crowe and Leonardo DiCaprio in Rabat in Morocco, rehearsing a scene we were going to shoot the next day." He rubs his eyes in disbelief. "This year has been insane."

'Stardust' opens today