The Blue Angel was the first sound film made in Germany, and was shot in both German and English simultaneously.

It was based on Heinrich Mann’s novel, Professor Unrat, and despite director Josef von Sternberg dispensing with almost two thirds of the book – in order to concentrate on the professor’s obsession with Lola – the author actually approved wholeheartedly of the final film.

Marlene couldn’t sing the line, ‘Like moths around a flame’, without the second word sounding like ‘moss’.  After (allegedly) 253 takes, von Sternberg gave up and instead masked the line by having a customer loudly ordering a drink over it.