Two of the stars of Britain's most successful film comedy ever have written their own sitcom – and it's a little bit feminist, finds Adrian Lobb

In a claustrophobic top-floor room at Three Mills Studios in east London, a key pub scene is almost ready to shoot on Chickens, a new Channel 4 comedy pilot. "Full rehearsement, everyone," announces Simon Bird, delaying proceedings by a good half a minute until the giggling has subsided. Set in the first world war, Chickens stars and is written by two actors from The Inbetweeners: Bird (the geeky Will) and Joe Thomas (the frequently humiliated Simon), as well as Jonny Sweet, last seen playing David Cameron in More4 spoof When Boris Met Dave. Little do Bird and Thomas know that by the time the show is screened, they will have topped the UK box office with The Inbetweeners Movie, in which the four sex-mad but hapless adolescents go on their first "lads' holiday"; the film took more on its opening weekend than any other British comedy in history.

Despite Chickens's period setting, the writers haven't exactly exhausted themselves researching this, their first sitcom. "I did a history degree once," says Thomas, holding court at the back of the catering bus as the other two swap gags. "I didn't specialise in this period, but all history is basically the same, isn't it? It famously repeats."

Anyone who baulked at recent anomalies in The Hour, when modern idioms slipped into the 50s drama, will once again be reaching for their etymological dictionaries. Bird points out that "we don't say clunge" (The Inbetweeners' memorable term for the female genitals) but all admit that historical accuracy was not their top priority. "We didn't want to let the old-school language get in the way of being funny," says Thomas. "So we wrote it as we speak, then went through taking out anything that seemed really incongruous."

Chickens finds the actors playing Cecil, George and Bert, the only men left in the Kent village of Rittle-on-Sea, their peers having gone to fight for king and country. As the village suffers its first losses at the frontline, conscientious objector George (Thomas), a teacher, is ostracised for refusing to dish out corporal punishment at the local school, flat-footed Cecil (Bird) bemoans a lack of beer, and caddish, cowardly Bert (Sweet) sets his cap at a grieving widow. There was "only ever going to be one candidate to play the louche scoundrel," says Sweet, who even in real life seems to be channelling Terry-Thomas, toying with his pencil moustache and affecting the drawling speech of the archetypal bounder.

If the period setting is a surprise after the excruciating dissection of contemporary adolescence that is The Inbetweeners, that's nothing compared with hearing Bird's description of the show. "Our hope, and the thought behind it, is for it to be a quasi-feminist sitcom," he says. "When we originally came up with the idea, there was a worry that it could be a bit misogynistic – this idea of us as the only men left and isn't it horrible living in England now it's full of women. But you see, actually, that the women cope very well. It's the men that don't."

"They are three pathetic men in a village full of people that all hate them," agrees Thomas. "Hopefully, you end up empathising with them, because their social prospects are impossible, really. People throw things at them in the street."

"It is very much based on our own life experience," deadpans Bird.

In fact, Chickens is partly based on their own experiences. The three cast members shared a house for two years after leaving Cambridge University, a domestic arrangement mirrored in the new comedy.

"We have gone full circle," says Thomas. "I think we all secretly want to live together again, so we've written a sitcom where we have a little cottage. But we had to decide who would play the housewife figure – and I did do a lot of the washing up."

"I didn't do a damn thing," says Sweet, proudly. "Every night Joe would cook us spaghetti, serve it to us at our table, then he would pour our glasses of wine. Afterwards, Simon and I would retire while Joe would wash up."

Much of the groundwork for the writing took place on the third floor of the Royal Festival Hall in London ("It would be very difficult to concentrate when there was a samba band in," says Bird). Though comparisons to The Inbetweeners will inevitably be made, they will be misguided, says Bird. "We didn't write The Inbetweeners, we are just in it. We love it, we are proud of it, but it is not our voice or our own distinct sense of humour, so there was never a danger of us doing something similar. Chickens is a step away from that more grossout comedy." There's certainly no scene comparable to the indignities Thomas is regularly subjected to in The Inbetweeners – walking down a fashion-show catwalk with one testicle hanging out being a memorable example.

Of the plot, Bird simply says: "We don't want to give too much away and ruin it, but we can tell you, for instance, that the water in George's cottage goes a bit brown. Be sure to tune in!" If a full series is commissioned by Channel 4, Thomas hints that the suffragette movement could make an appearance: he is keen to flesh out the roles of the supporting cast, notably The Thick of It's Joanna Scanlan, as Civilian Relief Committee chair, and Felicity Montagu – best known as Lynn in I'm Alan Partridge – as Merial, an unlikely object of Bert's affection.

"Most period drama is so earnest," says Thomas. "A lot of it is about making yourself take seriously things you wouldn't normally. You would not usually care about the various romances of some landed gentleman. Well, we are trying to make something that actually is serious less so."

Sweet agrees. "Yes. We are trying to trivialise the Great War, when people fought for our freedoms." And with that, they head back to the set, looking dapper as you like, locked in a serious top-level discussion about the potential expansion of Bird's facial hair in any future series.

• Chickens is on Channel 4 at 10.30pm on Friday