KEY POINTS:
If it had been a hazy, nostalgic 1970s trip with funny accents and quaint fashions, then "I wouldn't have done it," says John Simm.
"There were some very dark things going on in the 1970s - racism, strikes, the Birmingham Six, the Guildford Four - and we need to reflect that in Life on Mars."
Simm, 36, one of the best British actors of his generation and long a cult star and unlikely sex symbol, has been threatening to hit the big time for quite a while.
State of Play raised his profile but it has been the time-travelling cop show Life on Mars that put him on the map.
In November, Life on Mars won best drama series at the International Emmy Awards. And Hollywood producer David Kelley (Ally McBeal) is planning to make an American version.
Although Simm's career has gone through the roof, you sense he's slightly horrified that Life on Mars has made him so bankable. "I've never done anything so mainstream and glossy before," he says.
Simm is bad at being famous. He rarely goes to premieres and he and his actress wife, Kate MacGowan, nearly didn't get married because they loathed the idea of being splashed across Hello! magazine.
"I don't do things for money," he says, sighing at his own foolishness.
Simm has real street cred. Before becoming a professional actor he started a band, Magic Alex (named after the Beatles' electrician), and toured with Echo and the Bunnymen in the early 1990s.
After he played New Order frontman Bernard Sumner in Michael Winterbottom's 2002 film 24 Hour Party People he was invited to sing on stage with the band.
Because of his roles, audiences often assume Simm is a bit of a lad. But he trained as a classical actor and his interests are eclectic. He has started going to ballet and his favourite painters are Van Gogh and Jackson Pollock. Family life is very important. He and MacGowan live in Crouch End in London with their 5-year-old son, Ryan. Simm says that filming Life on Mars in Manchester for two summers was tricky. "It was hard coming back to London for Sunday lunch, trying to cram everything into one day off. I can't possibly do that again."
Simm, born in Leeds in 1970, grew up in the Lancashire mill town of Nelson. After his parents split up, when he was 11, he would accompany his entertainer father when he toured the northern clubs.
Simm became a talented guitarist but never enjoyed the spotlight. Acting is easier, he says, because you can pretend to be someone else. "But in a band, on stage, there's nowhere to hide. I used to just stand there and stare at the floor."
After drama school his breakthrough role came in 1995 as a psychotic teenager in Cracker. In his 20s he played sweet-faced, hedonistic young men (Danny in The Lakes, Jip the clubber in Human Traffic) and became an alternative sex symbol.
More recently he has excelled in gritty roles such as in Michael Winterbottom's Wonderland and Abi Morgan's Bafta-winning drama Sex Traffic, about Eastern European girls forced into prostitution in the West.
"I think Sex Traffic was a really important piece of TV," he says.
"They even made a documentary called The Real Sex Traffic. Suddenly it was an issue, and that's wonderful."
Simm hates talking about his personal life - he once dated Emma Bunton, and the papers have never let him forget it. But in person he is funny and modest.
In contrast to his naff 1970s wardrobe in Life on Mars, Simm is a snappy dresser with a weakness for Versace.
He laughs when I suggest that Life on Mars is an unacknowledged gay love story between his character, Sam, and his boss, Gene, played to great acclaim by Philip Glenister. "In a way, friendships at work are a kind of love story."
But then Simm is refreshingly un-macho. During our interview some drunks start baying outside the window. "Knobheads with football scarves on," he sighs. "Sorry. I hate feeling snobby, but you think, 'You morons'."
Simm has had his moments, too. He went a bit "ballistic" clubbing and taking ecstasy in the 1990s. He gave up clubbing when Human Traffic fans started making his life a misery, but says he is alienated by youth culture today. "I don't recognise kids any more - they've started going crazy and knifing and shooting each other."
In the old days, he says, you got a clip around the ear. "My 5-year-old's already going 'bang-bang-bang' with his Power Ranger and chopping people's heads off.
"When I was 5 it was the Clangers and Sooty. There's no innocence any more. I feel really sorry for them."
These days, just having Simm's name above the titles is a guarantee of quality. When the producers first pitched Life on Mars they suggested Neil Morrissey and Ray Winstone as the leads. No one got too excited.
But when Simm's name came into the frame, the project was snapped up. Audiences love the un-PC humour and 1970s jokes. But there is ambiguity, too. Has Sam really gone back to the 1970s, or is he in a coma, or dead?
Simm believes the series appeals to a key fantasy. "Everyone dreams about going back in time and meeting their parents when they were young. It's that thing of, 'Could you change the future?"'
Although he promised himself a long break after Life on Mars, he was offered the chance to play Van Gogh in a Channel 4 film, The Yellow House, opposite John Lynch as Gauguin. "There was no way on earth I could turn it down. The day before they told me I had a beard, but I shaved it off to have a facial and go on holiday.
"When I heard I'd got the job, I was frantically looking in the mirror and going, 'Grow, grow'. And he went on a crash diet to get his favourite artist's emaciated look.
Although the BBC is planning a spinoff to Life on Mars - called Ashes to Ashes, set in the 1980s and starring Glenister, Simm is bowing out. "My instinct tells me not to hang around too long."
He would like to do some comedy "in warm weather - preferably on a beach. I always seem to be doing drama in horrible brick locations."
And for years he's been wanting to play a proper villain. The problem is that Simm still looks 35 going on 15. But finally he's got the chance: he's just been cast in Dr Who - as the Master, the Doctor's evil nemesis.
He'll be quite brilliant, of course, but heaven knows how he'll cope with a whole new horde of obsessive fans.
On Screen
* Who: John Simm, star of Life On Mars
* When and where: Series final, 8.30pm tomorrow, TV One
- INDEPENDENT
