It doesn't in any way tarnish the memory of the late, great Nelson Mandela to say that this biopic, however reverent and well-intentioned, is a bit of a dud. The official adaptation of Mandela's 600-page memoir, it attempts to chronologically dramatise a whole life and decades' worth of South African social unrest and political change in a little over two and a quarter hours of screen time. Which means that most scenes are less than a minute long. You can't tell a meaningful story like that.
After some cursory exoticism among the Xhosa tribe, we see Mandela leave his childhood home to become a successful lawyer in Forties Johannesburg. His political awakening comes shortly after, when, in a moment of clarity, he notices that the law treats blacks unfairly.
His first marriage is similarly abrupt: he says hello to a woman in a crowd and they go straight to bed together, are married with children a few short scenes later, and divorced a moment or two after that. The film turns Mandela into the Solomon Grundy of 20th- century world leaders.
Mercifully, the pace slows just a little after Mandela's trial in 1964, and the first truly powerful and emotionally charged scene is the one in which this vital, passionately life-loving but self-sacrificing man is shown the cramped and dingy Robben Island prison cell in which he expects to spend the rest of his days.
The English actor Idris Elba, although he doesn't much look or sound like Mandela, does bring a powerful physicality to the role – which is well suited to the early, by-any-means-necessary, revolutionary phase of Mandela's life, and is then translated into strength of character for the later, pacifist-statesman period. If nothing else, you come out of the film with a sense of the man's remarkable rectitude, forbearance and political intelligence. But then you probably already had it on the way in.