John Simm’s ideal Saturday night involves dancing and scantily clad women. But it’s not what you might expect. The actor, who made his name as a drug-fuelled clubber in the British film Human Traffic, is hooked on ballet. “I’m obsessed with it. I know it sounds weird, and I haven’t told anybody this before. It started with The Nutcracker but I saw Gisele the other night. It’s just so beautiful to look at.” He looks a bit sheepish as he makes this admission. It’s certainly odd to see his sharp features, familiar from edgy dramas such as State of Play and Cracker, soften as he enthuses about a performance of Sleeping Beauty. After all, he’s best known for scowling his way through, as he puts it, “gritty serial killers for Channel 4”.

But maybe he’s lightening up a bit. His latest role, in the hit BBC drama Life on Mars, is certainly a departure for him. As time-travelling cop, Sam Tyler, Simm is transplanted to 1973 after a car accident. The show has been a surprise success, due in part to the nostalgia factor. Everything is perfectly rendered: from the Curly-Wurlys in the corner shop to the Deep Purple album tracks on the soundtrack. As Simm says, “It was a real trip being on set at first because it really was like stepping back in time. This was also something fun and a bit more mainstream for me, a proper prime-time glossy thing.” But although less serious than his usual fare, he nevertheless found it hard work. “I’m in absolutely every shot, and I’m either confused or disorientated or chasing someone. It was exhausting.” He grins. “I’m constantly having to emote – that’s the word – and run around in Cuban heels.”

Ah yes, the Cuban heels… The fashion in the show, all leather jackets and massive collars, is as well observed as the other Seventies details. Simm took it all in his stride. “Some of the shirts were a bit dodgy, but there was a lot of fun to be had with all that.” By his own admission (and borne out by his relaxed attitude on the shoot for these pictures) he’s a bit of a clotheshorse. “I think I’m probably a closet label snob. I like Paul Smith – even his shoes are great. Versace is good, too. Recently, I decided to start dressing like a grown-up, but nobody seems to have noticed yet.”

Maybe that’s because, despite his penchant for playing darker, hard-bitten characters, there is an aspect to Simm, 35, that makes you imagine him still wearing shorts. It’s a little-boy-lost air that goes some way to explaining why he’s become a bit of an alternative sex symbol. More than one female friend, told that I was going to interview him, smirked and said, “Oh, I like John Simm.” It’s a very British appeal (in the school of Dennis Waterman) that doesn’t rely much on conventional good looks but on a kind of everyday charisma.

This ordinariness defines Simm. He went to school in Nelson, a small industrial town in Lancashire, and he has never been comfortable with fame. “It’s never rested well with me. Now everyone is watching Life on Mars, so I’m getting stared at all the time. That’s why I stare at the floor a lot and end up walking into lampposts.”

Perhaps it was Human Traffic that brought him the most obvious notoriety. “People would plonk themselves down next to me and shout, ‘Nice one brother!’ in my face.” It stopped him going clubbing for good – which by his own admission was probably a good thing. “I went ballistic in the Nineties going clubbing. We were so bad, full-on. It makes people these days look like lightweight big mouths. Pete Doherty – he goes on and on about it, but he’s just a loudmouth hotheaded lightweight as far as I’m concerned.”

Nowadays he lives a much calmer existence in Crouch End with his wife, the actress Kate Magowan, and their son, Ryan. Future plans include theatre (“some Pinter or some Shakespeare”). And despite loathing Hollywood (“they are so full of shit”), he wants to do more films and would go over there for the right role. But the next stop is filming the second series of Life on Mars. Or as Simm neatly puts it, “Going back to the future.”

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