“That morning, Jim Sams, clever but by no means profound, woke from uneasy dreams to find himself transformed into a gigantic creature.” Ian McEwan’s enjoyable, cockeyed Brexit satire opens by tipping a gigantic wink to Kafka’s Metamorphosis, a work it in no way resembles. The set up is that a cockroach wakes up in No 10 after a big night, finds it is a hungover and very Boris-like prime minister, and, once it gets used to the unpleasant feeling of having an internal skeleton and a fleshy tongue in its mouth, sets about steering the UK into a popularly acclaimed national disaster. The bug is helped by the intuitive discovery – something to do with the pheromonal cockroach hivemind, I guess – that most of the cabinet are also now secretly cockroaches.