T here is a small boy in a Broadway café who has no idea who Andrew Lloyd Webber is. Or perhaps he knows just enough to want nothing to do with him.

Lloyd Webber is sitting nearby when he overhears a mother ask her fractious son whether he would like to see one of his musicals that evening.

“No,” says the boy.

“Behave yourself, then,” replies his mother.

Lloyd Webber recounts the exchange with evident relish. After a lifetime of spectacular success, he can still be reduced to a parental punishment.

“I always tell myself those sort of stories,” he says. “Because it’s all very well, all of that, you know?…