The Edinburgh Fringe has a habit of throwing up weird and wonderful physical comedy shows that are left wide open to interpretation. A few years ago it was Natalie Palamides and her egg-chucking show Laid, which may or may not have been about pro-choice. This year it is Frankie Thompson's Catts, which could be about gender, identity or mental health. Or it could just be a gloriously silly tribute to the Andrew Lloyd Webber musical.