This isn't funnier than the TV series just because it's louder

Like our very own mini-Entourage, the BBC Three sitcom Bad Education has come to the end of its natural life after three seasons, and there’s no more certain funeral than watching its carcass heaved across the multiplex screen. The joke – posh teacher, lairy kids – isn’t funnier just because it’s louder. In fact, it feels blown up to the point where the whole thing becomes a blur, like a dicey best man speech filmed using constant crash zoom.

Jack Whitehall’s idiot history teacher, Alfie Wickers, already feels like a glaring anachronism, a New Lad fit for some men’s style magazine think-piece circa 2012. He begins the movie, which Whitehall co-wrote, supervising a class trip to Anne Frank’s home in the Netherlands: queue-jumping, magic mushrooms and absconding wackily with a life-size Anne mannequin ensue.  Somehow, despite winding up confused and in a canal, Mr Wickers is given permission to redeem himself with a field trip to Cornwall, the county at whose expense a large proportion of the script’s hit-and-miss riffs get targeted.

There are jokes about incest, intimacy with livestock, and the closest thing to a gay in the village being some old duffer in a pub corner who ordered a spritzer that one time. This is all easy stuff, and thinly funny. But when Alfie gets mistaken for a torch-bearing member of some radical separatist group, the plot doesn’t thicken. In all honesty, it’s pretty thick to start with.

Whitehall opts to overact, but hasn’t figured out how to do it skilfully or well, and his overselling of every predictable reaction shot grates on the nerves at feature length. He’s shown up by co-stars who know exactly how to sock their parts over, which is to say almost everyone except Mathew Horne: the standouts are Iain Glen, as a smuggler fit for villainy in Enid Blyton, and especially Joanna Scanlan, as the gorgonishly overprotective mother of class swot Joe (Ethan Lawrence). This character is something like Sheila Broflovski (Kyle’s mother from South Park) crossed with Miss Trunchbull from Matilda, striking fear into the school board with her rape alarm and ever-handy pepper spray. Scanlan’s a great sport, even submitting to an unlikely indignity with a hamster that doesn’t bear describing. But she wins the act-off with Whitehall so roundly we wind up on her side by accident.

Fans of Edgar Wright’s Hot Fuzz may note the slavish care director Elliot Hegarty has put into producing a facsimile of it, right down to a scene with an angry swan (it’s the same swan). There’s a passing acquaintance with wit in the odd throwaway line – Alfie’s nasty old private school chums include a guy called Dave (“short for the Earl of Daventry”). But the classroom stereotypes – the gay one, the Asian one, the disabled one – remain banter delivery devices, walking (or rolling) punchlines, and the lazy characterisation of all their roles makes those recent St Trinian’s films look like Kind Hearts and Coronets.  Did it all have to be predicated on such weird hostility to mums, too? What Bad Education mostly needs is to grow up.