Historically speaking, British sitcoms rarely transfer well to the big screen, though the lure of a built-in audience is always an attractive proposition for financial backers. With that in mind, the surprise box office success of The Inbetweeners Movie in 2011 (which ended up taking nearly as much money in the UK as The King's Speech) is probably directly responsible for The Bad Education Movie, a film version of the BBC Three terrible teacher comedy starring Jack Whitehall. Sadly, there's very little of any merit here, unless you're a Whitehall completist interested in seeing prosthetic recreations of his balls on multiple occasions.

Right from the start, director Elliot Hegarty's film falls into a common trap of big screen upgrades and removes the characters from the familiarity of their small screen environment. In this case, that means disastrous, down-with-the-kids teacher Alfie Wickers (Whitehall, who also co-writes with Freddy Syborn) taking his suspiciously small class (only seven pupils get speaking parts) on a school trip to Cornwall after the completion of their GCSEs, accompanied by a pushy mother (Joanna Scanlan) who's determined to get Alfie sacked when he inevitably messes up.

Whitehall has his idiot posh-boy routine down pat and there's game comic support from Scanlan, who has to endure various humiliations too depressing to list here. The kids are all fine, but none of them are called upon to do anything other than react to whatever Whitehall's up to, and the film completely wastes a colourful supporting cast that includes Harry Enfield, Talulah Riley, Iain Glen and The Wire's Clarke Peters.

The plot begins promisingly but degenerates into a confusing and offensive mess that paints the people of Cornwall as revolutionaries-slash-terrorists-in-waiting. As for the jokes, they rarely rise above the level of bad taste / gross-out humour; it says something that the best gag involves Alfie being dared by his obnoxious ex-schoolmate (a wasted Jeremy Irvine) to tea-bag a swan. It all adds up to a dismal disappointment, with Whitehall's likeably goofy comic presence failing to compensate for the poorly structured script and general lack of laughs.

General release from Fri 21 Aug.