Christmas performances are traditionally the stuff of rank, ego-driven amateurs desperate to impress easily-pleased audiences that are prepared to overlook their obvious deficiencies.

But that’s enough of Vince Vaughn in Fred Claus.

No, director Debbie Isitt’s enjoyable Yuletide yarn skilfully manages to avoid any charges of vulgar consumerism or money-grubbing cynicism by virtue of its determination to simply enjoy itself.

It’s like spending a cheery Boxing Day hour or two with a convivial uncle as he enchants the kids with party tricks while keeping the adults entertained with a nod and wink.

Martin Freeman plays Mr Maddens, a Krimbo-hating Coventry primary school teacher obliged to put on a nativity despite his last effort being savaged as a minus-two star disaster by Alan Carr’s tweedy local drama critic.

To make matter worse his little helper is “village idiot” Mr Poppy (a scene-stealing Marc Wootton), a classroom assistant whose puppyish exuberance wins him legions of fans among the anklebiters but the contempt of the cynical Maddens.

Things really hit rock-bottom when the hapless Krimble show director, seeking to trump the drama teacher of a snobby rival school, misleadingly announces that his ex-girlfriend Jennifer (Jensen) - now a Hollywood producer who dumped him under the mistletoe for a life in California – is coming over to check out the production and maybe make it into a film.

Entirely improvised (Isitt whittled down 240 hours of footage) and employing dozens of children who have never acted before, this enchants by virtue of its sparkling spontaneity, the very antithesis of Hollywood method.

Freeman is an old pro and natural improviser but it’s Wootton’s Tigger-like classroom anarchist that is the movie’s real heart and soul, a force of nature who unashamedly identifies with the hopes and fears of the kids.

There’s pleasing support from Carr – the comic who looks like he’s chewing Stonehenge – and Pam Ferris as the well-meaning but defeated headmistress.

However, it’s the pure, device-free performances of the talented cast of children that makes this a winner and that rare thing – a Christmas movie that actually captures a pocketful of its spirit.

Tim Evans