It’s irresponsible, demeaning and glib to expect an actor to be the character he has been pretending to be. But, there are times when the two have been the making of each other to such an extent that to disentangle them requires effort. That’s why, when people meet Philip Glenister for the first time, they brace themselves for the rough rhetoric of Seventies cop DCI Gene Hunt. He, you may remember, is the one who said, in the recent hit TV series Life on Mars: “As long as I’ve got a hole in my arse, there’ll never be a female Prime Minister.”

Though light on the skills of political forecasting, you had to admit he was effective in youth crime control. His manifesto in this area of work: “Behave or I’ll come round yer house and stamp on yer toys.” With the huge success of the two series of Life on Mars, watched by seven million, Gene Hunt became an icon of political incorrectness, and an unlikely heart-throb to boot. If you judged him from today’s standards – which was the game at the heart of the show – his style transgressions were brazen: Cortina Mk III GXL, sideburns, camel coat, leather slip-ons. Glenister got the man bang to rights. He even managed to remind Sheila Hancock of her late husband John Thaw, star of The Sweeney. Other offences to be taken into account included researching his delivery with old footage of Brian Clough, football management’s counterpart to DCI Hunt.

“In the force today it’s all red tape and pen-pushing,” he says – “he” now being Glenister rather than Hunt. “They dread making arrests because of all the form-filling which that entails. The other day there was a story about someone who’d been beaten up by six youths, and the police said unless you’ve got evidence, forget it. Some estates they’ve simply given up on. They just don’t go there.”

Add to this a pronounced nostalgia for the suburbia of North-west London where he grew up, and it does start to sound as if the casting was psychologically as well as physically apt. But then: “Of course people do look back and go, ‘Aahhh’, but the reality was not so nice. The three-day week was coming up, and the miners’ strikes, the unions had the nation in their grip, there was no leadership and the country was a mess.”

Having become a distinct cult hero as the throwback policeman, 44-year-old Glenister now heads for the 19th century and the virtual reality of Mrs Gaskell’s Cranford in the BBC mini-series based on three of her books. He goes there as Mr Carter, estate manager for Lady Ludlow (Francesca Annis), a working-class man who has bettered himself through the good fortune of a grammar-school education. As Glenister points out, Mrs Gaskell’s portrait of a largely female community fighting to preserve its show of gentility against the downward drag of poverty has been regularly overlooked by TV producers in favour of Dickens and Austen.

“But she’s brilliant on class,” he says, “one of the greats of that period [1850s]. Along with Elizabeth Fry and Florence Nightingale, she was one of the first generation of feminists.” Her community of Cranford is based on the small Cheshire town of Knutsford, where she was brought up by her aunt. The fictional place is indeed a kind of feminocracy. Mrs Gaskell puts it rather more vividly, describing it as “in the possession of the Amazons”. Here, she writes, “vulgar is a tremendous word”. It is some 30 miles from the great industrial town of Drumble (Manchester), from where the narrator, Mary Smith, recalls with sharp-eyed affection the pretensions of Cranford society.

So once more Glenister finds himself in the Manchester environs of a particular period, and in the best of company. Here, embittered old thing Miss Matty Jenkyns (Judi Dench), in the shadow of her morally superior sister Deborah (Eileen Atkins), rues her thwarted love for Thomas Holbrook (Michael Gambon).

In the London narrative of his own life, Glenister was the sibling who didn’t go to grammar school, as did his elder brother Robert, but to one of the fledgling comprehensives of 1975. “It was a new system,” he recalls. “I was one of the guinea-pigs. No one knew what to expect. They promised the earth and delivered eff all.” The boys’ father, John, was a TV cameraman, who also had form with police series by working on Z Cars. He became a director and scored a hit with The Six Wives of Henry VIII. The family lived in Harrow, and Glenister remembers being literally in the shadow of the public school on the hill. “You’d see them round town with their boaters, bunking off school, smoking fags. Oh, they were so posh.”

He never thought about acting until he went to see Robert in something called Killing Time at the experimental Soho Poly. “It started with someone saying the line, ‘Life is a shit sandwich’, and I thought, hmm, yes, that’s all right. Robert always wanted to act, from the age of seven, whereas I was always quite sporty – tennis, football, discovering girls. But my dad used to take me and my best friend Paul to TV Centre, and we’d see the Dr Who Tardis and the Colditz set, and the smell of the studio, which was, I don’t know how to describe it, it was just incredibly nice and technical – that really got into me, and to this day I love that magic atmosphere and smell you get in Shepperton or Pinewood.”

He studied for three years in the Eighties at Central School of Speech and Drama in London, along with Graham Norton and Rufus Sewell. He shared a flat with fellow Central graduate Jamie Glover, daughter of Julian Glover and Isla Blair, and met his now wife, the actress Beth Goddard, at Jamie’s birthday party. They have two daughters, aged 5 and 3, and live in Richmond – Sheen to be precise – where he says he couldn’t be happier.

Although Gene Hunt is his best-known role, he was already an established TV presence. He was in State of Play and Clocking Off (playing the factory boss), and worked alongside John Simm (Sam Tyler in Life on Mars) in both those series. He was also the photographer in Calendar Girls. There was a certain amount of theatre, including Beautiful Thing, Jonathan Harvey’s triumphant story of gay love on a council estate, and a West End play in 2002 called The Feast of Snails in which he played a young stranger visiting David Warner’s reclusive billionaire. The play was a disaster. Not many people saw it as it closed well before schedule. When I say that I was one of the few who did, he looks briefly surprised, then groans and says, “Oh shit.” He got into it, he says, partly because he was just becoming a first-time father, and partly because he didn’t read the script properly.

He was a good way into the first Life on Mars script – about page 15, he reckons – before he saw anything in it. “I was reading it, and thinking, ‘Well, it’s another cop show, isn’t it?’ And then suddenly, bang, he [DCI Sam Tyler] has this terrible crash and wakes up in 1973. From then on, we’re cooking on butane. I couldn’t put it down. When I spoke to the writers [Matthew Graham, Tony Jordan and Ashley Pharaoh] about it, they said they just sat for a week in Blackpool, saying no cop shows, no vets, no doctors. Then they had this brilliant idea of combining a time-travel show with a police series. That was the stroke of genius.”

Glenister hasn’t quite finished with DCI Hunt. Nor has the nostalgia industry. One publisher, Bantam Press, has even brought out a spoof manual, The Rules of Modern Policing (1973 Edition). This note on understanding criminals is a fair representation of the tone: “There’s a lot of talk creeping in these days about the need to understand the criminal’s mind.” Glenister plays this great non-hugger of hoods again next year in Ashes to Ashes. This moves the action on to 1981, where, with a strong sense of déjà viewed, we will find a 21st-century female detective, DCI Alex Drake, stranded after an accident. In the course of this we might unravel the enigma surrounding Hunt. Does he exist? Did he ever, or was he merely a figure of Tyler’s traumatised imagination? If there is a question mark over Hunt’s actuality, it is no fault of Glenister, who made him so blokishly, beerily there for us. And if the burglary figures fall in Sheen, you surely can’t just put it down to coincidence.

Cranford begins on BBC1 at 9pm on November 18

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