Henry Williamson’s unsentimental 1927 children’s story following the life of river otter Tarka was always ripe for film treatment. But the author heroically fobbed off the likes of Disney in favour of relative unknowns: husband-and-wife team Janet and David Cobham. The reason for his choice is clear in the Cobham’s permed-hair, platform-heeled interviews from the ’70s, included here among the meagre extras. As they snuggle an otter on their knee, the duo are utterly pragmatic about depicting the realities of an endangered, hunted species. Maybe that’s what makes Tarka such an enduring tale – and the source of so much childhood trauma. Getting real animals to ‘act’ before Jean-Jacques Annaud even dreamt of it and using Peter Ustinov’s dulcet tones to narrate, the Cobhams created a delightful, unflinching and remarkable film that will still induce blubbing in the knee-highs. Go on, traumatise your own kids with it.