Retired politicians have cornered the market in biographies of great leaders. These books annoy historians because they pinch their research and sell more copies. They tend to be uncritically admiring too, claiming that a lifetime’s political experience qualifies them to hand out praise of the great man. Roy Hattersley’s new life of David Lloyd George is different. It begins conventionally enough but, as it goes on, Hattersley becomes increasingly critical of his subject, making this a more interesting book.