A favourite photograph of one of my grandsons shows him astride his rocking-horse, wearing one of my old hats, a rifle and a pistol in his tiny hands and the reins between his teeth – a miniature copy of John Wayne in the iconic scene from True Grit, in which he challenges the outlaws to draw their guns and face him. As soon as I saw it, I realized I had infected him with my lifelong obsession with Westerns, on screen and on the page. I thought: ‘If that child says “Fill yore hands you sonsabitches” I’m in trouble.’