‘A biography of Darwin must, chiefly, be the biography of an idea.’ A N Wilson’s observation, made nearly a third of the way through this longish work, may be well founded. But it is belied by the content of his book, which abounds in incidental detail about Darwin and his life without offering any clear statement of the idea of natural selection – the core of Darwin’s theory of evolution. Many readers will learn facts about Darwin they did not previously know. I had no idea that he had a makeshift privy built behind a curtain in his study in order to cope with his chronic flatulence, or that (assisted by his nephew Frank Darwin) he dealt with letters from admiring correspondents in what Wilson describes as a ‘lavatorial fug’. Some readers may be interested to learn of Darwin’s place in the changing class hierarchies of Victorian England, a theme to which Wilson returns again and again.