There's a moment in Peep Show, the ridiculously addictive Channel 4 sitcom about two dysfunctional flatmates, where Jeremy (Robert Webb) dreams of dumping his long-time companion Mark (David Mitchell) for a more socially acceptable friend. Jeremy yearns to join the mainstream rather than being trapped in perpetuity with Mark in what he terms "our own little puddle."
Of course, the joy of Peep Show is that, try as they might, Jeremy and Mark can never escape from their own little puddle. They will never swim in the mainstream. Like the characters in Sartre's Huis Clos or Jack Lemmon and Walter Matthau in The Odd Couple, they are doomed to live together forever.
Peep Show, "the best British comedy on TV", according to Ricky Gervais, has won a mantelpiece-endangering number of awards. In the process, it has turned Mitchell and Webb – who also have their own BBC2 and Radio 4 sketch shows – into just about the hottest comedy double act currently on television.
My rendezvous with the two stars is at a suitably un-mainstream location. They are filming the sixth season of Jesse Armstrong and Sam Bain's series, which begins next Friday at a disused military post office in a far-flung corner of north London. Tumbleweed blows across the car park.
In person, the actors are far more intelligent and likable than their Peep Show personae, although they do admit to some overlap with their alter egos. "You get a gold medal for not asking as your first question, 'how similar are you to your characters?'" smiles Webb, who unlike the eternally fancy-free Jeremy, is married to Abigail, an actress and has a baby daughter, Esme. "But there is one key similarity: in my opinion, David tends to worry too much, and in his opinion I tend not to worry enough."
The 36-year-old Webb goes on to explain how vital it is that the characters remain condemned to their life of loser-dom. "The moment Mark and Jeremy learn anything or become content, it's the end of Peep Show. Life moves on, but they never do. It's like Jerry Seinfeld said about his own sitcom: 'no hugging, no learning'."
Mitchell, who is unmarried and lives in an ex-council flat in London with a lodger, chips in: "Mark and Jeremy's circumstances may change, but their attitudes never do. It would end the joke if they were sensible. It's important in a sitcom that things always return to the status quo. Sam and Jesse don't have to excise much hugging and learning from their scripts.
"In American sitcoms, the underlying attitude is, 'everything's OK'. In British sitcoms, the underlying attitude is, 'everything's maudlin and disappointing and inescapable'. That's the world view of a civilisation that has been knocked off the top spot and continues to meander. I imagine American sitcoms will have a lot less hugging and learning in a hundred years' time."
The characters in Peep Show are marooned by their own intransigent personalities. Mark is an uptight, tweedy financial adviser who is a serial failure with women, while Jeremy is a louche, self-absorbed aspiring musician, who is a serial failure with women. However much he attempts to get down with the kids, Mark is an utter square – by the brown cords and brogues shall ye know him. He looks like a Young Conservative in search of a husting. He is prey to all sorts of nerdy obsessions, such as military history, chess, and Star Wars ("if you ask me, Skywalker was bloody lucky turning off his guidance system").
Jeremy is a self-deluded, workshy, wannabe hipster. In one episode, for instance, he urges his flatmate to experiment with drugs: "It's not the Eighties, Mark! No one's dying in a puddle in an advert". Jeremy's speciality is spectacular acts of egotism, followed quickly by even more spectacular acts of self-justification.
In the new series, Mark and Jeremy are both desperately hoping that the other has got their joint ex, Sophie (Olivia Colman), pregnant. They indulge in all sorts of risible displacement activities in an attempt to forget about their impending paternal responsibilities. Things are so dire that Jeremy even – shock, horror – contemplates getting a job.
On the surface, Mark and Jeremy are really quite reprehensible, self-serving people. So why do we warm to them? "Mark and Jeremy are not the most likable characters," concedes Webb, who first met Mitchell on a Cambridge Footlights production of Cinderella in 1993. "But we still like them because they give us all permission to be losers ourselves. They share this sense that there is this cosmic party going on somewhere else to which they're not invited. We all feel like that."
Mitchell, 35, is making quite a name for himself as the prince of the panel-game and recently received the BBC accolade of his very own Who Do You Think You Are? episode researching his family tree. While his own parents were in the hotel business, he discovered that his father's family were sheep farmers in the Highlands and his great-great grandfather was a Gaelic scholar and minister. "I come from a long line of people who looked down on the peasantry and resented the aristocracy – and I hope to continue that mixed up, hypocritical attitude in my own life because without the middle classes there is no comedy."
Mark and Jeremy strike a chord, says Mitchell, because, "we identify with losers in this country. We don't style ourselves as winners. The standard projection of a British person is, 'I'm a bit shit, me. Oh look, a bird has just crapped on my head.'
"British social convention demands self-deprecation. It's a civilised approach that leads to a lot of communication problems with Americans, who think we really have low self-esteem and really believe we're rubbish. In British sitcoms, figures who aren't hapless are ridiculed. We're suspicious of people like Paul, Peter Egan's character in Ever Decreasing Circles, because nothing ever seems to go wrong for them. We don't trust people whose toast falls buttered side up."
Peep Show certainly reinforces the first law of British sitcom: failure is funny. Webb, who made a splash replicating Jennifer Beals' leotard-clad routine from Flashdance on Comic Relief earlier this year, reflects that, "Mark and Jeremy are massively ill-equipped for life, and we relish that. Losers are more interesting – they give viewers a sense of consolation.
"Nothing is funny about winners. Comedy has to be about conflict – crying, for instance, can be incredibly funny. J R Ewing winning in Dallas is no fun unless we can also see Cliff Barnes suffering. Everyone has flaws, and everyone is funny when put under the microscope. Gordon Brown is the most successful person in the country, and yet he's hilarious when he tries to talk and smile at the same time. Have you seen him on YouTube?"
The added frisson of Peep Show derives from the fact that it gives us privileged access to Mark and Jeremy's darkest thoughts. The show has provided women with many scary peeps into what is really going through men's minds. Be afraid, female viewers, be very afraid.
Mitchell says that listening in to their unvoiced ideas is a great release for us. "Mark and Jeremy think the things that most of us would like to think but would never have the nerve or the towering selfishness to think.
"There's a lot of Mark and Jeremy in all of us, and we all feel better about ourselves because we see our traits represented in them. People come up to me all the time and say, 'I'm just like Mark'." At which point, presumably, Mitchell runs away from them, screaming.
Above all, the stars argue, Peep Show is a love story. It's the ultimate exemplar of "can't live with you, can't live without you". "Could Mark and Jeremy ever live apart?" Webb asks. "Never! They need each other to confirm their world view. Mark knows there are lots of things wrong with him, but at least he's not Jeremy. And Jeremy thinks, 'no matter what's going wrong in my life, I'm not that guy'. They are a massive solace to each other – 'I may be in my hole, but look at your hole!' In fact, of course, they're both in the same hole!"
Mitchell reflects that, "it's a love story. Mark and Jeremy are effectively married to each other. A woman ought to come between them, but she would never succeed."
Even though the sixth series is about to begin, the actors do not think Peep Show is running out of steam – in fact, quite the contrary. "The older Mark and Jeremy get, the funnier it becomes," says Webb. "You're not allowed to share a flat with another man when you're edging towards your late 30s. When 40 is on the horizon, society says, 'no!' That puts more pressure on them, and pressure equals comedy."
Mitchell concurs that, "there will always be some looming crisis for Mark and Jeremy. When Niles finally got together with Daphne in Frasier, what was there to bother him? There was nothing left to drive him to distraction."
So what's next for Mitchell and Webb, who have been called "the new Fry and Laurie"? "You hit your late thirties, and all of a sudden people decide you should be in a comedy drama," Webb observes. "'Now you're nearly 37, it's off to Norfolk for you, my boy. We want lots of sweeping shots of the English countryside. Let's get rid of the laughter track, calm it down and mawkish it up. Let's go a bit Sunday night'."
In fact, what Mitchell and Webb have in the pipeline is more of the same – if it ain't broke, why fix it? They are already planning further series of both Peep Show and That Mitchell and Webb Look. They have also just brought out This Mitchell and Webb Book. How do they fit it all in?
"We're both bone idle, so we love deadlines," Webb smiles. "We never miss them – that would be the thin end of the wedge. Miss one deadline and we'd soon be sitting around in our pants flinging rubbish at each other. We'd be just like Mark and Jeremy."
'Peep Show' starts at 10pm on Channel 4 on Friday 18 September.