There’s a scene in Alfred Hitchcock’s Marnie in which Tippi Hedren is emptying a safe while a cleaning lady silently drags her mop towards her. Can Hedren, playing the disturbed Marnie, slip down the stairs before the woman turns her head?

I felt a twinge of the same panic last week interviewing the composer Nico Muhly, whose opera Marnie — based more closely on Winston Graham’s novel than on Hitchcock’s film — was given its world première by English National Opera last Saturday.