In the jargon of composing, the songs in musicals are “diegetic” – in the context of the scene, such as a nightclub, the character is singing naturalistically – or “non-diegetic”, where the tunes represent ­conversation or inner thoughts.
Kander & Ebb’s Cabaret (Kit Kat Club, London), one of the greatest stage and movie musicals, has many numbers – “Willkommen”, “Don’t Tell Mama”, “Money” – diegetically sung in 1930s Berlin at the Kit Kat Club (into which the Playhouse Theatre beside the Thames has been transformed inside and out) by Eddie Redmayne’s creepy, sleazy MC or Jessie Buckley’s English chanteuse, Sally Bowles.

The biggest innovation of Rebecca Frecknall’s revival is to make the public numbers more internal: Buckley spews out “Mein Herr”, a comedy song, as a furious response to her latest male betrayals. Another fresh idea is that the MC, who usually becomes ever more outré as Berlin descends into Nazism, here reinvents himself as a blond Aryan ­heterosexual, an all too plausible search for safety in conformity.