The Sopranos was not the only concluding TV drama that left its devotees baffled last year. Also departing on an enigmatic note was BBC1's time-travel cop show Life on Mars, in which a sensitive, modern-day policeman, Sam Tyler (played by John Simm), was transported back – either bodily or mentally (we were never to be told) – to the world of law and order as allegedly practised in 1970s Manchester. As Tyler asked himself each week, "Am I mad or in a coma or back in time?"
Tempering the disappointment felt by those who enjoy their dramas with definite endings was the knowledge that the hero of Life on Mars was going to have his own series. But it wasn't nice Sam Tyler that seven million viewers had fallen for, but his unreconstructed Seventies copper sidekick, DCI Gene Hunt. Played by Philip Glenister in a camel coat, kipper tie and black leather driving gloves, Hunt was the runaway success of the series – not bad for a man assessed by his 21st-century counterpart as being "an overweight, over-the-hill, nicotine-stained, borderline-alcoholic homophobe with a superiority complex and an unhealthy obsession with male bonding". (To which Hunt replied: "You make that sound like a bad thing.")
"When Life on Mars came to end through natural causes, I think we all thought: 'Hang on, this character, Gene Hunt, is a fairly extraordinary man and we're not quite done with him yet'," says executive producer Jane Featherstone. The BBC was quick to agree, and commissioned a spin-off, again named after a David Bowie song: Ashes to Ashes, which not only relocates our Neanderthal copper from Manchester to proto-yuppie London, but also dumps him into one of the most eventful 12 months of Margaret Thatcher's premiership. It's safe to say there'll be culture clashes – another of Hunt's famous utterances was: "There will never be a woman prime minister as long as I have a hole in my arse."
The year 1981 was a time of inner-city riots as well as Charles and Diana's wedding, while those looking for fashion pointers need only look as far as London's Blitz club, where New Romantics were poised to take over the style world. On the other end of the fashion spectrum, Bucks Fizz won the Eurovision Song Contest – all rich pickings for a time-travel drama with a keen eye and a savvy sense of humour.
"I'm a child of the Eighties," says Featherstone, "and so is Matthew [co-producer Matthew Graham], and we sat down and thought, 'Let's plonk Gene Hunt in the Eighties and see what happens.' We thought 1981 would be particularly interesting because of the Scarman Report and the whole different attitude towards policing that was just beginning."
Lord Scarman's inquiry followed the Brixton riots of April 1981, which had ignited largely because of the sort of racist policing lampooned in Not the Nine O'Clock News's "Constable Savage" sketch. This had Griff Rhys Jones's copper arresting a Mr Codogo for "possession of curly hair and thick lips", a joke that would no doubt have left Gene Hunt feeling nonplussed.
Updating the characters and concept of Life of Mars was one thing, but it was providing Hunt with a self-confident, 21st-century female sidekick that gave Featherstone what she calls her "light-bulb moment". "Putting him with a woman was the moment when we thought: 'you know what, this thing could actually work,'" she says. "The dynamic will be different, and everything will feel different, but we'll build on the essence of Life on Mars."
And Glenister thought he knew just the woman for the job – Spooks actress Keeley Hawes. He says: "Very early on when we were talking about doing this, Jane Featherstone said she wanted to have a woman, and I said that if she could get Keeley I would be very interested. I thought she'd be just right."
Glenister's instinct turns out to have been spot on. Hawes's Alex Drake, a self-confident hostage negotiator, reveals hitherto hidden aspects of an actress who often seems rather aloof on screen. Here she's both earthily comic and sexy, and, as Featherstone says, she brings a whole new dynamic to the Life on Mars concept. "I think Ashes to Ashes is funnier, actually. It wasn't particularly designed that way, but I think Alex Drake is a funnier character, and that's down to Keeley."
This tallies with the original desire for a vibe that "crossed Moonlighting with Miami Vice", but didn't answer the tricky question of how to get Hawes's 21st-century character into the 1980s world of Gene Hunt. Their solution was to start Ashes to Ashes in modern-day London, where Alex Drake has been investigating the tape handed over to the police by Sam Tyler in the final episode of Life on Mars. "All that tape business in the final episode [recording instances of Gene Hunt's alleged professional misconduct] was deliberate because we knew by then that we were already going to be making Ashes to Ashes," reveals Featherstone. In the opening episode of the new series, Alex Drake is shot during a hostage negotiation, "waking up" in 1981, dressed as a hooker, at a party on a Thames riverboat hosted by a City big shot. Hawes has been given a wonderful look, reminiscent of Guy Bourdin's fashion shoots of that era for Vogue. I ask Hawes if it's time for an early Eighties fashion revival. "If you walked through Hoxton [dressed like that] right now nobody would bat an eyelid – everybody looks like that now," she corrects me.
Locations were harder to source than clothes. When I congratulate Featherstone on finding one of the last undeveloped warehouses with a view of Tower Bridge, she tells me the derelict lot was in fact further east, near Bermondsey, with Tower Bridge added using CGI. "It was really hard finding locations in London. In Manchester it was easier, but London is so developed."
If authentic-looking Eighties locations proved hard to find, they were luckier with human relics of the decade. New Romantic impresario Steve Strange plays himself in the second episode, set in the Blitz Club, while Zippy and George from Rainbow have slightly sinister cameos. The late Lord Scarman is played by Geoffrey Palmer, in a key scene in a later episode.
Is the show reactionary? After all, by 1981 the BBC had already screened GF Newman's damning quartet of films about "rotten apples" in uniform, Law and Order, while Roger Graef's influential 1982 documentary about insensitive handling by the Thames Valley Police of rape cases was just around the corner. And, of course, such high-profile miscarriages of justice as the Guildford Four, the Maguire Seven and the Birmingham Six were partly a result of Gene Hunt-style policing methods.
But Glenister thinks there is something refreshingly straightforward about the character. "I think it's his lack of self-awareness in a very image-conscious age; this man comes along and just says: 'This is who I am.' It's quite refreshing." Hawes is also a staunch defender. "Everybody gets it from Gene Hunt. I don't think you could say: 'you're being racist, or you're being homophobic...' And he has such generosity of spirit. I think it might be different without that."
But of course Gene Hunt is a reactionary figure – a reaction to the contemporary perception of the police as ineffective, pen-pushing social workers. If so, it seems to have struck a note across the Atlantic, where LA Law and Ally McBeal producer David E Kelley has just finished filming an American version of Life on Mars. Meanwhile, Featherstone would love to produce a second series of Ashes to Ashes.
What about a future series updating Gene Hunt to the early Nineties – perhaps named after a song by Bowie's band Tin Machine? Featherstone laughs in horror at the thought. "Don't we need to get further away from the early 1990s? God, please don't, not yet..."
'Ashes to Ashes' starts on Thursday 7 February at 9pm on BBC1