In Act III of Nixon in China, John Adams’s opera on the 1972 meeting between the leaders of two superpowers, the military pomp and political choreography of a state visit dissolve. This is the diplomatic after-party, a dreamscape of reminiscence and regrets with a soundtrack of cocktail piano and muted brass. Bored by the fug of narcissism, Chiang Ch’ing, aka Madame Mao, orders a change of tempo: “Give me your hand, old man. We’ll teach these motherf***ers how to dance!”

More than 30 years after the Houston premiere of Nixon, the woman who wrote that line stands by it. The poet and priest the Rev Alice Goodman “learnt to swear at my mother’s knee”. A librettist is “a subordinate position”, she says. “But