So now we know. In a bittersweet final visit to Fenchurch East, Gene Hunt – the Guv – was revealed to be a young rookie PC, shot dead on Coronation Day in 1953; the ghost copper buried in a shallow Lancashire grave who has been haunting DI Alex Drake in the final series. Viewers who suspected that all the CID characters in 1983 were already dead had their theories confirmed: Ray hanged himself; Chris was a young uniformed PC shot dead; Shaz was stabbed by a young would-be car thief. And then, of course, there's Alex, the comatose modern-day cop, struggling to get back to her daughter.
"The place that Alex finds herself in is a plane between heaven and Earth," explains Ashes co-creator Matthew Graham, who wrote the final episode, speaking for the first time about the secrets of the drama. "When we discussed the philosophy behind it we decided that, seeing as how the cosmos was infinite, everybody who dies can afford to go to some kind of purgatory plane that is relevant and significant to them. So we liked the idea that coppers with issues would go to a place designed for coppers. And a coppers' paradise surely has to be The Sweeney, or The French Connection if you're an American. That's the place where you've got all the freedoms and, therefore, all the chances to make all the big mistakes that could lead you to hell. But all the good decisions would lead you to heaven."
Through five series, Hunt's role in this police purgatory has been that of an archangel saving souls – with DCI Jim Keats, the gatekeeper to hell or the devil himself, appearing in this series as his nemesis. So did Hunt have his own police hotline to God? "We both agreed that Gene isn't appointed by anyone," says Graham. "He has done this for himself. He's re-invented himself and built a world that is very potent and real that draws others in. But Gene doesn't know he's doing it. He doesn't go off into a room on his own and talk to God. He just obeys some animal spiritual instinct inside him."
The clues to the mystery at the centre of Ashes to Ashes and its predecessor Life on Mars were seeded throughout the series. "Ashley [Pharoah, the co-creator] never wanted the ending to be unguessable because that would be a cheat," says Graham. So at the start of this final series, a digital clock turning to 9:06 recorded the moment DI Drake died in her hospital bed – the choice of numbers was a random decision when writing at his computer, although later his mother reminded him that was the time he was born. "We always knew Alex wasn't coming back," Graham says, explaining there were only ever three endings: that she woke up, she woke up and chose to go back again, or she died. The first was dismissed because "we didn't think anyone would want that because we didn't want that with Sam", and the second because "we did that in Life On Mars". Which left only the final option. "If she could flit about and go home when she wanted to, when it suited us, it would then feel slightly too much like Alice In Wonderland," Graham says. "Whereas in this, it is Alice In Wonderland. But Alice doesn't get to go home."
Hunt's storyline has also been alluded to throughout the drama – you'll remember that he has been seen cradling dying coppers. "We didn't want anything to come too much out of left field, except that maybe Gene's a kid," Graham says. Hunt had forgotten his previous life as a "skinny lad" gunned down during his first week on the beat, until DI Drake unearthed his grave near Hyde. Gene's "carefully constructed world" was then temporarily demolished by Keats, as he smashed up Hunt's CID office to reveal the hidden universe all around.
As Hunt led his team to their corner of paradise – Life on Mars's police local, the Railway Arms – original Mars barman Nelson, a spirit guide in more ways than one, was there to meet them. Meanwhile Hunt returned to his CID world to greet another confused modern-day detective in a mirror of Sam Tyler's arrival in the very first episode of Life On Mars.
There had, of course, been intense speculation about whether Simm would reprise his role as Tyler for the conclusion of the sequel. And Graham and Pharoah did give it consideration: "There was originally a version where John came back. It was never scripted but it was storylined," Graham says. "John was going to come out of the Railway Arms instead of Nelson. Everyone seemed to really like it. We were all quite happy and excited about it.
"Then we suddenly thought that it would steal all of Keeley's thunder, it would undermine Ashes as a show and also Sam's supposed to be dead, so he should be in heaven. It suddenly made him seem like a superhero – he could go from purgatory to heaven and back again. So we decided not to do that." They didn't approach Simm, then? "We never asked him."
And so, finally, after two series of Life on Mars and three of Ashes to Ashes, Gene Hunt's story has been told. But the show's co-creators and writers spent eight years in their own purgatory, developing Mars before it was finally commissioned by the BBC. The result has been a complex drama, stuffed with references: Alice In Wonderland and CS Lewis's Narnia books have been influences, along with The Wizard Of Oz.
Fans who agonised over the significance of Alex Drake's ruby red shoes, however, will be surprised to hear that they were simply a joke on the part of costume designer Rosie Hackett: "There's also a bit of Paradise Lost going on in there," adds Graham. "With Jim and Gene you've got two men, one of whom (Hunt) doesn't know what he represents, and the other (Keats) who absolutely does know what he represents but wants to trick the other one by pretending to be less powerful than he is. I wanted to find almost a modern version of a Milton-esque poetry to it, particularly in the way Keats talks."
Some viewers may have been too busy enjoying Hunt's politically incorrect ways to notice. The gruff Gary Cooper fan surprised his creators by sparking the passion of some female viewers – there's even an online group called Hunt's Housewives – the admiration of some men, and leaving others obsessed with Gene and Alex's (or Galex's) relationship. "I'm still amazed that girls find it romantic, this big hulking bloke in a dated suit, that there could be anything even closely resembling a sex symbol," Graham says. "I find that baffling. It's great but I just don't understand it."
So what next for the pair? Talking to Graham ahead of the final episode, he says he will have been watching it this evening with Pharoah and the show's producers at his home: "We're going to have some cold beef salad and some champagne and just raise a glass to it." Visitors will have to mind Sam Tyler's headstone, which sits at the top of the stairs, now flanked with the Gene Genie's snakeskin boots. For his part, Pharoah has the Railway Arms pub sign and is about to take delivery of one of the bullet-ridden doors from Hunt's Audi Quattro.
And it will surely be a relief for the pair that the ending that was plotted right at the very beginning of Life on Mars has finally been revealed. "It's been hard keeping the secret," Graham admits, "even my family didn't know. I don't tell them anything. So they know nothing in advance. It is an emotional ending. I guess we very rarely finish a show, where you really know that you are saying goodbye to a group of people."
So Gene Hunt will definitely not be returning to television? No, says Graham he will not. Although, "if Hollywood came calling ..."
