Six years ago, Ian McKellen was starring in my play The Cut at the Donmar Warehouse. Before the first preview performance, he told me: “I really like to get my laughs. But it’s your play and you must tell me if I’m bending the play out of shape.” I promised that I’d watch out but thought, “If you can find any laughs in The Cut — the most dense, oblique play that I’ve ever written —then good luck to you.” But I also promised myself that, one day, I would write something for Ian that would give him as many laughs as I could possibly write.