You want to know how The Sopranos ends? Here it is: the screen goes black. Okay, it’s a little more complicated than that. Indeed, so much more complicated that the US entertainment industry and significant parts of the internet have been talking about little else since the last series aired in June. The final episode of the mobster show has become television’s grassy knoll.

Less than three months after it appeared, there are at least eight joke versions on YouTube: in the style of The Blair Witch Project, The Exorcist, the Austin Powers films, a retro drinks commercial and, with a chilling inevitability, Star Wars. An e-mail essay claiming that every extra in the finale has been seen before on the show began circulating the day after the broadcast. One blogger believes the songs chosen for the final season, if noted in order, offer an answer; another questions a moment when Tony, Carmela and AJ eat their onion rings in the style of a communion wafer; and far too many people have been analysing the lyrics of Journey’s Don’t Stop Believin’, used in the finale.

Al Gore discovered that he would be on a plane to Istanbul when the episode aired, so he begged Brad Grey, the chairman of Paramount (distributor of An Inconvenient Truth) and an executive producer of the show, for an advance copy. Grey finally relented and had a (Halliburton-made) steel case containing a copy delivered to the tarmac where Gore’s plane was waiting. The case was locked with a code, and the former vice-president had to phone Grey’s office from the air for the access number. Rudolph Giuliani then called Grey to complain that he hadn’t been given similar treatment.

David Chase, the show’s creator and executive producer, fled the country shortly before that fateful night. There was no price on his head, of course; he was just crashing at the one luxury he splashed out on in 10 years on the show, a large house in southwest France. He came back to America for the TV Critics’ Awards, where he poked fun at the conspiracy theorists by telling reporters, “The walrus is Paulie.” Two months on, he’s still bemused.

“When this started, I thought the best we could get would be a decent cult following, loyal but sweet,” he says. “Mostly, I thought it wouldn’t succeed, that it would be suffocated by the critics. In fact, we got only one bad review. When we finished the pilot, then the first series, we kept saying: there is no way they’re going to keep on letting us get away with making this. But here we are. In the week of the finale, with a war in Iraq and car bombs in London, the American media focused on the ending of The Sopranos.” He sounds slightly horrified at all he has wrought.

Of course, the shower of attention is because, as has been said before, the show effectively changed television. It was the first to place gangsters at the centre of the narrative, with cops as characters just passing through. Tony Soprano was a mobster, but one aware of his lot; as stressed as the average man, in therapy over anxiety, worried about the family business, trying to do the best for his kids. You came for the mob, but you stayed for the human stories and emotional pain, drawn out with acidic comedy by Chase and his carefully whittled-down team of New Jersey writers.

As such, it paved the way for the current crop of antihero dramas: The Shield, Dexter, Eddie Izzard’s The Riches. And by setting the budget for series one at $2.5m per hour, it allowed CSI to follow with its $3m+. Most important, by making television cool and unfolding luxurious story arcs across whole series, it attracted acting, writing and directing talent across from the movies and onto the small screen.

In a parallel universe somewhere, Chase’s agents didn’t persuade him to dig up a two-hour movie script about a mobster in therapy who finds out his mum wants to whack him and take it to broadcasters after his years on Northern Exposure came to a close. And Chris Albrecht at HBO didn’t see the potential andpersuade him to plot the story out across 13 episodes. In that universe, we might have Lost, Desperate Housewives, House and Ugly Betty, but they would be based on the templates drawn up for Walker, Texas Ranger and The X Files.

None of which impresses Chase. “I don’t watch television,” he says shortly. “Not a single other show. Just The Sopranos. I much prefer to go to the movies.” Indeed, the element of the Sopranos finale he seems proudest of is its cinematic feel. He was always frustrated that they mixed the soundtrack on a movie system, then compressed it for TV. All his life, he’s wanted to make movies. From the moment he broke with his overbearing Italian-American parents – fans know Tony’s murderous matriarch, Livia, is based on Chase’s mother – and pursued a career in the moving image, it was the big screen he had his eye on. But that was in the 1960s. Somehow, The Rockford Files, Northern Exposure and The Sopranos got in the way. Now 62, he’s finally got producers snapping at his scripts.

“I’ve got a few ideas,” he says carefully. “I’ll just see if people plan to suck all the vitamins out of them.” One thing he is constantly asked about, of course, is a Sopranos movie. Sex and the City is going to have one, and The X Files two, so why not Tony and the boys? There’s a pause as he chooses his words. “The reason I’m so cautious about this is, I say these things, then they say, ‘David Chase is jerking our chain. He’s trying to lead us on that maybe there will be a Sopranos movie.’ I’m not.” He sounds weary and frustrated. “There is no plan. I don’t think we should do one. But everybody reserves the right to change their mind, or miss something and want to go back to it. I’m realistic enough not to rule that out, but I would say the chances are really unlikely.”

For now, there’s the final nine episodes to enjoy. Perhaps because Chase has so little regard for television, he’s delivered his most textured, complex season to date. It begins with Tony, Carmela, Tony’s sister Janice and brother-in-law Bobby taking a break in the Adirondacks and musing over mortality, then unravels into that episode, with more tension than ought to be legal. So, Mr Chase, what is the secret of that Sopranos finale?

“If you look at the final episode really carefully, it’s all there,” he explains. “This isn’t Lost. When you see it, we’ve shed light on everything. The one thing that really puzzles me is why a British newspaper would be so interested in a show about New Jersey Italian-Americans.” Perhaps it’s because they represent rebellion without rejecting capitalism, I venture. “That’s what I always thought.” He sounds satisfied. “Their motives are the same as ours – it’s just their methods are the ones we wish we had the balls to use. Sometimes.”

The final season of The Sopranos is on E4 on Sundays, 10pm, and will move to C4.

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