His career peaked while Edward Heath was still PM, yet Alice Cooper is still, at 70, selling out the big rock sheds.

In between telling a familiar story – smalltown boy finds fame, does too much drink and drugs, cleans up – this fond biography explains why.

It’s the personality of the man born Vincent Furnier – he is self-aware enough to realise that draping yourself in snakes and clowning around with fake blood and guillotines on stage is all a bit of a giggle, as much pantomime as ‘shock rock’.

Elton John and Iggy Pop are among the voices turning up to sing the praises of this old trouper, in a documentary refreshingly free of talking heads.