16 May 2009: Boozing. Nasty flats. Cat murder. Worryingly, Pulling creators Sharon Horgan and Dennis Kelly draw on their own lives, finds Amy Raphael

Sharon Horgan has the filthiest laugh you’ve ever heard. She may be one of those melancholic comedians behind closed doors, but here in a small room somewhere in west London, she seems to find the world very funny. Usually relaxed in interviews, she’s a bit of a live wire today and can’t sit still. As soon as she walks into the room she shouts, “Fuck, it’s cold!” and pulls on her jacket.

Next to Horgan, sitting perfectly still, is Dennis Kelly. Horgan, 38, and Kelly, 40, met a decade ago. Put simply, he showed her a script and they started writing together. The result was Pulling, which made its debut on BBC3 in 2006. It was, quite simply, brilliant. Here were three women in their 30s behaving badly, getting insanely drunk, sleeping with awful men. The script was sharp, the acting superb. As the gorgeous but self-obsessed Donna, Horgan led the way; as her flatmates Karen and Louise, Tanya Franks and Rebekah Staton were equally convincing as wayward alpha women.

In 2007, Pulling was nominated for a Bafta. Horgan won a British Comedy Award. The critics were mad for it. And the BBC decided not to commission a third series. The second series was broadcast in spring 2008 to yet more acclaim but the BBC wouldn’t budge. They did, however, agree to a one-hour special, airing tomorrow. Horgan and Kelly claim not to know why a third series was denied them. “Maybe our haggard old faces don’t fit on BBC3 any more,” says Horgan. Did they try to reason with the BBC? “We cried. We threw ourselves at their feet,” claims Kelly. “Does that count?”

The inspiration for Pulling came from the lives Horgan and Kelly led in their 20s. Horgan left Ireland in her late teens, attended some second-rate acting schools, earned cash as a waitress and, in her late 20s, studied at Brunel University. She had been to convent school and lived on a turkey farm; Kelly was brought up in New Barnet and got a first in drama and theatre arts from Goldsmiths. Despite their different backgrounds, they had similar experiences. Horgan: “Both of us lived in low-level shared accommodation for years.” Kelly: “With nutters.” Horgan: “In rubbish relationships.” Kelly: “And being rubbish at relationships.” Horgan: “And being in shit jobs. Those experiences had to be exploited and expunged.”

If the women in Pulling are skidding off the rails, the men are plain pathetic. The opening scene of the special shows Donna and her boyfriend Stephan, a vile toff, having sex on a bed covered with money. Horgan insists that while she’s a huge Alan Partridge fan, the scene wasn’t inspired by the infamous Steve Coogan tabloid tale in which he also threw cash on a bed before having sex. “No way! I had no idea about that story!” OK… but did Kelly have to stop Horgan having too much fun with the weak male parts. They both laugh. Kelly: “The weird thing is that I probably enjoyed it more than Sharon. We don’t really think about gender when we’re writing though; we just write characters…”

“I got a perverse pleasure in thinking of specific things I’d experienced that I could then use in the script.” Kelly continues. “The scene in the first episode of series one, in which Karl [Donna’s fiance] sits on her knee as she’s trying to break up with him – well that happened to me, only the other way round. I just trying to tell this old girlfriend it was over and she got on my knee, wouldn’t listen…”

Although they say they just write characters, Horgan and Kelly admit that they were aware of the dearth of strong female comedy roles. Horgan: “There was nothing out there for me; I had to give myself a break! Peep Show has very funny female characters but they’re generally girlfriends or incidental women who are just helping the story along.” Kelly: “When we were writing Pulling, we wanted to make sure the comedy was with the women. Even with comedies that are about women, it’s often the blokes who get the funnies. In Pulling we even err too much the other way and make the men too two-dimensional. But it was important for the women to get the funny lines.”

What is perhaps most striking about Pulling is its lack of a moral centre. Even in Peep Show, which is equally dark and dysfunctional, David Mitchell’s Mark offers some rectitude. Horgan: “I guess there isn’t a moral centre because Dennis and I don’t have one.” Kelly: “That’s scary. Fuck. We need to get a moral centre. Shit. It’s really true. But we do try to make sure we don’t get nasty for the sake of it. We make sure there’s a bit of heart. The most difficult scene in the last series was the cat killing. We agonised over it.”

It was awful, I say. Killing a cat with a brick. Kelly: “The characters themselves were upset by it…” Horgan: “The cat was also very terminally ill.” Very terminally ill? Not just terminally ill? Horgan unleashes her dirty laugh: “It was very, very terminally ill.” Kelly: “More terminally ill than usual.” Horgan is serious for a moment: “I got very nervous about that scene. Dennis had the balls for it but I didn’t. I emailed [Peep Show co-writer] Jesse Armstrong and asked what happened when the guys ate a dog. He said nobody gave a shit. But cats are different.”

While Horgan is currently considering American comedy scripts, Kelly has returned to writing plays – he is a prolific, award-winning playwright – and a film. Horgan is happy enough to be an actor for hire – as she was in Channel 4’s Free Agents – but would rather act in something she’s had a hand in writing.

The Pulling special suggests that the BBC may yet regret their decision not to commission a third series, but how much material did Horgan and Kelly actually have left over from their grim 20s? “We did talk about the danger of getting further away from the lives of the characters,” say Kelly. “Sharon is married with two kids and I haven’t had a drink in seven years. When we first started writing together, we thought we couldn’t write without something mystical called… booze.”

As the Guide gets ready to leave, the conversation turns to Morrissey. Horgan saw the Smiths in a small pub in Ireland in 1984 and Morrissey two years ago. “I couldn’t take my eyes off him for a second,” she says. “There’s something very Elvis about him now.” Kelly agrees. “There is something Elvis about him. But that person is not the person with gladioli in his back pocket. I felt betrayed when they started saying it was all ironic. Why do you snort with derision?” Horgan is bent over double with laughter.

Is this what it was like when they were writing Pulling?

Kelly: “When we were in the edit, we did tend to sit there pissing ourselves.” Horgan: “Not everyone should be laughing all the way through their jobs but…” Kelly: “A doctor certainly shouldn’t. Or an undertaker.” I leave them laughing so much they can barely speak.

• Pulling special, Sun, 9pm, BBC3