The biopic Mandela: The Long Walk to Freedom is a timely tribute, and an earnest and respectful and well-meaning one, but it does seem like a very, very long walk indeed. It’s a slog, a plod, a trudge uphill, and of all the things you may have wished to say to Nelson Mandela, given the opportunity, what you will find yourself saying here is: ‘Put your bloody skates on, man.