It’s lunchtime a couple of weeks before Christmas. Past the tree in the glitzy lobby of Claridge’s hotel in London ambles a man who, in his octagonal glasses, workman’s jacket, jeans and trainers, looks a little out of place. Once installed in his room, however, Tony Kushner is entirely in his element. Insights on art, history and politics pour out at the slightest prompting. He cites writers from Conor McPherson to Robert Lowell, gives a lightning-quick insight into Othello (too cruel a play, he says, for him to catch National Theatre’s new production on this trip) and, in the 50...