Oooh-er, Matron!

Billed partly as surreal soap and partly as innovative drama, the new Channel 4 comedy Green Wing was filmed in real hospitals - to the bemusement of patients

The sick and the lame queuing at Basingstoke General Hospital last summer may not have realised it, but the four junior doctors they saw emerging from a chauffeur-driven Mercedes were not beneficiaries of some fantasy New Labour rise in pay and conditions for the medical profession. In fact, they were comedians and part of Channel 4's bright new hope for its suddenly Friends-less, Frasier-less and Graham Norton-less Friday nights.

The sick and the lame queuing at Basingstoke General Hospital last summer may not have realised it, but the four junior doctors they saw emerging from a chauffeur-driven Mercedes were not beneficiaries of some fantasy New Labour rise in pay and conditions for the medical profession. In fact, they were comedians and part of Channel 4's bright new hope for its suddenly Friends-less, Frasier-less and Graham Norton-less Friday nights.

Green Wing is the ambitious and somewhat unclassifiable new comedy from the Smack the Pony creator Victoria Pile, and the end result of a lot of shuffling about of twin-battery packs. This is how Pile and her co-writers began to devise her new show more than two years ago - pushing battery packs, each with a caricature face stuck on with Sellotape, around her desk.

"Battery packs are marvellously weighty objects," explains Pile in her office at Talkback Productions, the scene of this unusual pastime. 'They're pleasing to shove around a table and act out scenarios with."

At this stage, these weren't even characters in search of a drama - let alone doctors. They were more like characters in search of an anecdote. "The plot came much later," says Pile. "We eventually did story arcs across wall charts in there," she continues, pointing to a larger office next door.

But then Green Wing has been a wonderfully unconventional project throughout, as we shall see later. Impressed by the success of Smack the Pony, winner of international Emmys and the first genuinely funny "post-feminist" sketch show (Pile prefers to describe it as "gender free" - it was, she says, the first comedy to "accept women as silly and sexy and self-deprecating, rude and clever"), Channel 4 handed Pile carte blanche. There was one proviso, however: the show had to have a narrative thread. It had to be more sitcom than sketch show.

Originally conceived as a traditional run of six, half-hour shows, Green Wing has mushroomed into nine episodes, each a generous 50 minutes long. Described in the press pack as "part-surreal soap, part-innovative drama", the show is set in and around a hospital, although this was only one of a number of possible backdrops when Pile and her seven co-writers (including her husband, Robert Harley) first started pushing their battery packs around.

"The hospital is incidental, really," says Pile. "I was looking for a home for a bunch of assorted characters and I happened to mention to Peter Fincham (then managing director at Talkback Productions; now chief executive of Talkback Thames) that something like a hospital would be ideal. He returned the following day and said: 'Channel 4 would be very interested in a hospital setting.' We were sort of presented with a fait accompli, really."

Indeed, one thing everybody involved is keen to stress is that Green Wing is not a medical comedy, or a "hoscom" as shows such as Scrubs, the dire TLC or the even more dire Doctors and Nurses seem to have become known. "If we get another series - and it depends on the ratings - we might even set it on a cruise ship," says Pile, and you sense she's only half-joking.

It's been two years since the original (unbroadcast) pilot was completed, and it says a lot about the project that Pile managed to hang on to the entire cast except Doon Mackichan, one of her triumvirate from Smack the Pony, who had since become pregnant. Parts of the 2002 pilot were even blended into tomorrow night's first episode (Pile says you can tell which they are by the differing length of actor Julian Rhind-Tutt's hair).

Rhind-Tutt, who plays a junior doctor, joins the likes of Tamsin Greig from Black Books, Mark Heap ( Spaced), Stephen Mangan ( I'm Alan Partridge), Michelle Gomez ( The Book Group), Pippa Haywood ( The Brittas Empire) and Sarah Alexander from Coupling, the largely uncredited "fourth member" of the Smack the Pony team. It's an impressive ensemble - a sort of pick'n'mix assortment from the best of recent British TV comedy.

"If you look at this show there are people from very different comedies," says Greig, who is best known for playing Fran in the dearly departed Dylan Moran sitcom Black Books, and who here plays the pivotal character of Dr Caroline Todd, the new girl on the wards. "At the risk of sounding like a wanker, comedy is about how you trust somebody - how they're going to play with you. It's very rare that you go on to a comedy programme and you've got that three months beforehand to muck about and workshop, and I think that trust shows."

Greig is referring to the most unusual process involved in bringing Green Wing to fruition. The performers workshopped their characters for 12 weeks before being handed their scripts, which they then acted out while being free to ad-lib material themselves. The cameras were then left running at the end of each scene, to capture any "business" that the actors spontaneously came up with. The writers then rewrote the scripts incorporating what they liked of what they had witnessed.

"Some of the performers felt more at home with this process than others," admits Pile. "Stephen Mangan, for example, is brilliant at improvisation. In fact, it's impossible to shut him up..."

Mangan himself says he found the choppy, sketch-like nature of Green Wing slightly disorientating. "We filmed in three different hospitals, so that's the only difference I really feel when I'm watching it - what hospital we're in," says Mangan, who plays the hospital lothario - a sort of 21st-century Leslie Phillips from the Doctor films of the 1960s, if the comparison isn't misleading. Heap's pompous consultant is perhaps another stock "hoscom" character, although there is nothing "stock" about Heap's gleeful, almost Pythonesque performance, which sent Green Wing off in unanticipated directions.

"We originally intended something much more subtle and observational - more like The Office," says Pile. "But once we had our cast in place we got rather carried away with their various skills. Mark Heap is such a comic genius - the idea of his having illicit sex in the office with Pippa Haywood's head of human resources just played into Mark's clowning hands, and he ran with it. We've ended up with something much broader than we first envisaged."

Not as broad as the posters for the show, now plastered across the country, might suggest. Somehow incorporating a stuffed camel, the posters also show the doctors playing roulette in the operating theatre - although the actors all have stories from their research (probably too libellous to repeat here) about what really goes on during operations. But the posters manage to make Green Wing seem much more juvenile than it really is. In fact, although never shy of the rude and lewd - witness Haywood on the vibrating bed in tomorrow night's episode ("Oh, it gets far worse than that," promises Pile) - the humour is far more sophisticated than the modern-day Carry on Nurse promised by the adverts.

"It's just delving into the familiarity of behaviour that rings bells with us," says Pile. "Like with Smack the Pony, it's all about observational details and quirks of behaviour. I think my personal taste does err on the side of the absurd as well, but the absurd has to be underpinned with authenticity."

That avowed authenticity stretches to such details as the lighting, not habitually the concern of comedy producers. "I have a personal hatred of watching shows where you're aware of the set, and for some reason television lighting in comedy shows has traditionally never been particularly realistic," says Pile. "Aesthetically it's much more satisfying to have natural daylight - to light areas more like a drama or a film than comedy. It's why we filmed it in real hospitals."

Green Wing was filmed at three hospitals - Basingstoke General Hospital (the most accommodating) and two in and around London. "There were people being wheeled past on trolleys on their way to serious operations," says Mangan, who plays anaesthetist Dr Guillaume Secretan. "And there were people coming out of serious operations, and we'd have to do our scenes really quietly so that we didn't wake up them up after their triple bypass operations. The NHS must be in a pretty shoddy state to allow us lot to wander round with bare arses up and down the corridors."

He adds: "I got bothered quite a lot when I had the doctor's gear on, with people asking questions. I'd say: 'Take a couple of aspirins and go home.'"

Moving in the opposite direction to the authenticity of the filming was the surrealism of the editing, with its unpredictable speeding up and slowing down of the action - occasionally both in the same sequence. "The editing became an additional comic device really, a third dimension to the comedy," says Pile. "A bit like making a pop video - certain elements we just indulged ourselves in because it felt good. But you can also show more than you could if you just played it all in real time - you get more biff for your boff."

And Green Wing certainly does give viewers more biff for their boff. If they don't find 50 minutes just slightly too long to be biffed and boffed, then Channel 4 should have a deserved winner on its hands.

'Green Wing' begins tomorrow at 9.30pm on Channel 4