I am not altogether sure why the editor keeps sending me books to review on filth, stench and defecation. I don’t think I have any greater interest in these subjects than is normal. Nevertheless, it must be said that this latest offering, a survey of worldwide lavatorial habits, is strangely fascinating. The Big Necessity is shit from beginning to end – but not in a bad way. In fact, Rose George’s bold claim is that ‘shit doesn’t have to be – and shouldn’t be – a dirty word’.