And for the first ten minutes of this "demented jukebox musical" – a spoof retelling of "Titanic" that raids the back catalogue of the Canadian singer Celine Dion – I felt sure we were heading ...

“I know you know the words because, let’s face it, you’re all gay,” says Celine Dion, her mic thrown towards the audience, one great throng of Titanic stans who’ve been waiting all night ...