The rather amazing true story of the white ANC activist Tim Jenkin and his audacious escape from Pretoria Prison in apartheid-era South Africa is told in this capable and well-carpentered movie from British film-maker Francis Annan, adapted from Jenkin’s own book. The film has something pleasingly traditional about it, with tense nailbiting moments, slab-faced guards, and touches of The Great Escape and Papillon.

With long hair and straggly beard, Daniel Radcliffe plays Jenkin and Daniel Webber plays his fellow ANC activist Stephen Lee, imprisoned in 1978 for their “leaflet bombs” – firecracker-type devices left in the street which send blizzards of leaflets flying. Their prison is tough, but as they are white, it is not as tough it might have been. Inside, Jenkin and Lee meet another political prisoner and future escaper: Frenchman Leonard Fontaine (a slightly hammy turn from Mark Leonard Winter). He is evidently based on the Egyptian-born French national, Alex Moumbaris, with whom the men actually broke out, although it isn’t clear why his character has been fictionalised and the others not.

Jenkin has an extraordinary brainwave: all the locks are of such an old-fashioned type that with enough cunning and patience, duplicate keys can be fabricated from wood in the prison workshop. And so the extraordinary business of designing and manufacturing these bespoke secret keys begins. In jail, the men meet the legendary ANC veteran and Mandela intimate Denis Goldberg, played by Ian Hart, and their disagreements about what an escape will achieve (which the film has amplified a bit) are where the grit of internal tension is to be found. Escape from Pretoria doesn’t amount to much beyond the prison walls but delivers a tough, muscular and watchable drama.

• Escape from Pretoria is released in the UK on 6 March.