Every season a couple of wonderful biographies emerge whose reviews and sales might lead one to believe that they will stay bestsellers for ever. A year or two later they are in no greater demand than thousands of other backlist titles. Examples of this might be Amanda Foreman’s Georgiana or David Gilmour’s Curzon. Both were rightly acclaimed, but after the flurry of reviews, after Christmas had come and gone, they joined others on the shelves as definitive works on rather specialized subjects whose future sales will be steady, but modest. This is not to derogate the books: it is just what happens.