The British Isles is acquiring some new additions. These nascent islets are not made of granite or limestone, but of agglomerations of wet wipes and mud. The largest is a metre deep, spans the width of two tennis courts and sits at a bend in the Thames by Hammersmith Bridge in London. It was measured last summer by volunteers from Thames21, a charity, which has been tracing the formation of such monstrosities for seven years. It reckons that there are at least nine wet-wipe islets in the Thames, and that smaller ones may be forming in the bends of other rivers.

Britons dispose of 11bn wet wipes a year. They clean the nation’s babies and homes, and help disinfect its hospitals and care homes. But they a