When I was about seven years old, my Dad took me to the cinema to see a film called ‘Dunkirk’ starring John Mills and Richard Attenborough, about the evacuation of hundreds of thousands of British soldiers from the beach at Dunkirk as the Germans overran France in the Second World War. It was one of the first times I had been to the cinema, and the film made a strong impression on me, particularly the scenes of helpless, terrified soldiers trying to take cover in the sand dunes as German planes dropped bombs on them and strafed them with machine-gun fire.