The Mitford Industry (as the author of this correspondence cheerfully labelled it) has been so prodigiously productive over the years that the mere sight of this enormous new volume takes one aback. Another 764 pages about the joys and miseries of that extraordinary clan? More about Nancy and Debo and Unity and the rest of them? The fact that it turns out to be a readable and enjoyable book is, of course, thanks to the personality of the writer. Jessica Mitford (always known as Decca) was a one-off. From her childhood in sheltered ignorance (Lord and Lady Redesdale did not believe in education for their daughters), by way of elopement with Winston Churchill’s nephew to a career as a left-wing agitator in the United States, she followed her own naturally rebellious nature.