In this age of Asbos, hoodies and teenage gang warfare it’s probably illegal to encourage youngsters to swear and be rude in front of adults, but this is exactly what the grown-ups behind School of Comedy plan to do. The show is billed as ‘an adult sketch comedy performed by 12-to-16-year-olds’. The lure of permitted profanity must certainly appeal to those not yet of an age to legally smoke or drink alcohol but is there much purpose beyond a giggle for the kids and open-mouthed shock among unprepared punters?

The show’s driving force, Laura Black, thinks so. As well as producing School of Comedy she’s also returning to Edinburgh with Silly Billy Bum Breath Strikes Back, the sequel to last year’s wildly successful sketch show for children, and outside of August runs comedy classes for children in London and teaches drama at a secondary school. If anyone knows how kids react on and off the stage it’s her.

‘These children are incredibly talented, and this is their forte: they observe adults,’ she says. ‘Kids that go off and play football in their breaktime might not be as exposed to what these children expose themselves to.’ So, while the show may be too much for audience members under 16, she feels her greenhorns on stage are well-grounded. ‘I have the full support of their parents. I workshop with the children, so the creations are coming from their minds and I’m not forcing them to do things that would be inappropriate. It’s almost better that they’re allowed to swear in my environment because I’m controlling it.’

Children are usually annoyingly good mimics, and the characters that make up the show have developed from impressions the kids worked on for the three-year gestation of the show. There’s the nouveau riche businessman and his inappropriately drunken wife hosting a dinner party, with a roll-call of guests including the geeky IT chap, the cross-dresser, the sex-mad male gymnast, the unemployed actress and the Latvian Eurovision Song Contest hopeful. The characters then spin off into their own sketches, combining the pleasingly silly with the uncomfortably dark – uncomfortable in part because of the baby faces on stage.

Black admits that the characters are ‘quite stereotypical’, but believes that the standard of acting carries the show. She says, ‘The thing is, once they’ve performed these characters, everything about them becomes adult. You forget very quickly that they’re little; it’s odd. I think the most shocking thing is the talent.’ Talent that’s already been recognised: 15-year-old George MacKay, who plays Sophia, appeared in the BBC’s Tsunami: The Aftermath, and Will Poulter – only 14 – stars in The Hitchhiker’s Guide to the Galaxy director Garth Jennings’ upcoming feature, Son Of Rambow.

In conversation, Poulter is articulate and expansive. ‘I’m playing an IT specialist called Philip who’s the annoying office guy,’ he says of his role in School of Comedy. He’s surprisingly perceptive on the separation between the adult character he plays and the fact that he’s still a child. He says, ‘There’s lots of adult comedy, and it’s not the fact that [our show is] ruder than most adult comedy, it’s the fact that we are kids. The characters we’ve been given are really, really good, so if it comes across that we’re adults, we should be able to get away with it.

‘Laura worked with us a lot on our body language and the way we speak, because we’d be slouching in our chairs and stuff like that. We’ve been practising being more adult in our actions, because if you come across as kids swearing, that’s not going to be funny,’ he continues. The workshops involved Black and Trippplicate, the double act of Morgan Lloyd Malcolm and Katie Lyons, who scooped a Writers’ Guild Award nomination from this very magazine last year, for their Fringe show The Receptionists. ‘We had our own ideas and they built onto it,’ says Poulter. ‘It was really really good fun, it was amazing!’

Caroline Poulter is one of those supportive parents without which there would be no show. ‘I have to say I was a bit shocked when I saw it the first time. It’s quite ‘adult’ for kids – you see them effing and blinding on the stage and you say, oh my, that’s shocking!’ Yet she appreciates the shock value, and that the material fits the characters. ‘I’ve never seen kids doing that kind of comedy before. It’s not what you’re used to hearing every day, but then they are acting and it’s part of the characters.’

There is, of course, the problem of what the wider world will make of the show, outside of the cosy environment in which it has developed. Scandal sells tickets at the Fringe, but those who indulge in it are usually better-equipped to deal with its consequences than a group of teenagers. Black is sanguine. ‘Half of me thinks, does it matter? But for the sake of the children, who have worked so hard with me on this, it’d be nice for people to get it.’

Both actor and director admit that School of Comedy pushes the boundaries, and Caroline Poulter lets on that some jokes about black and Jewish people had to be cut from the script after complaints from audience members. However, she counters that the jokes were in character, and that they didn’t offend her or a member of the cast, both of whom are Jewish. Perhaps some fear that such jokes are just too sensitive to be handled by young performers.

Black says, ‘We are pushing a few boundaries – it’s not Bugsy Malone. And if you push boundaries there’s always going to be one or two who don’t like it.’ Will Poulter agrees: ‘The writers have done it really cleverly, and built it in a way that’s funny, but it’s pushing the boundaries. It’s different from school plays and pantomimes, but we’re all really looking forward to it. We’re gonna be nervous whatever we’re saying in front of those crowds.’

School of Comedy, Pleasance Courtyard, 556 6550, 20–27 Aug, 1pm, £8.50 (£6.50).