Mary Lovell says in her new book that the extended Mitford family refers to the plethora of books about the doings of the six sisters as the "Mitford Industry". If so, it's an apt term - but it would be wrong to assume that those who launched and ran the business were all outsiders. Far from it: of the various books by and about the family, one of the best and most undeceived accounts of the grandparents, parents and seven children (six sisters and a brother, Tom, who was killed in Burma in 1945) is The House of Mitford by Diana Mosley's eldest son, Jonathan Guinness, and his daugher Catherine. Diana herself wrote a piquant autobiography, A Life of Contrasts; Jessica wrote memorably about the family in Hons and Rebels. Charlotte Mosley, Diana's daughter-in-law, has edited Nancy Mitford's wonderful letters; Sophia Murphy, Deborah Devonshire's daughter, has put together The Mitford Family Album.
This family business was founded by Nancy, the eldest, with her comic novels. The Pursuit of Love, published in 1945, was the one that brought her fame, and its successor, Love in a Cold Climate, continued the antics of the by-then famous "Radlett" family. Yet more than a decade before that, as early as Nancy's Highland Fling, in 1931, Lord and Lady Redesdale and their children were seeing themselves reflected in the fairground mirror of fiction.
The making of family memoirs, the plundering of the supper-table joke-kitty for the fictional bank account, usually takes place long after the protagonists have gone their separate ways into adult life, or (better) all the way to the grave.
But when Nancy started to write about her family, she still lived chiefly at home herself. Her three youngest sisters, Unity, Jessica and Deborah, were still in the schoolroom; Tom, the only son, stayed regularly for long periods. Only Pam (child number two) and Diana (child four, after Tom) had left home.
The impact of Nancy's novel on the family is well described by Jessica in her own book (though many years later, in 1960). When Lord Redesdale, in life a rather humorous and fond father, saw himself spoofed by Nancy as General Murgatroyd, "a man of violent temper, terror of housemaids and gamekeepers, who spent most of his time inveighing against the Huns and growling at various languid, aesthetic young men in pastel shirts loathing ... anyone or anything who smacked of the literary or the artistic", he did not protest much at the caricature. According to Jessica, he "rather loved being General Murgatroyd"; more significantly, he "became almost overnight more a character of fiction than of real life, an almost legendary figure, even to us".
So the myth was cast and Lord Redesdale - gleefully aided by his children - proceeded to play to type. His "Murgatroydish aspects" (Jessica's phrase again) became a source of endlessly reiterated and exaggerated anecdotes. The rest of the family followed suit, with an expanding web of jokes and stories - the wilder the better - that encompassed them all. The Mitfords may not yet have been famous to the rest of the world; but they were already special in their own eyes. While other people - cousins, friends - who remember the family in childhood often testify that the atmosphere was perfectly normal, actually rather jovial and accepting, the Mitford children felt exceptional, and set themselves to be so. It was as if Nancy had pointed the way: their cult of exaggeration, their only half-serious relation to the deadly serious things of life, the concept of a "tease", their highly competitive antics and achievements.
Their Pursuit (Nancy's title was given her by Evelyn Waugh, but he knew some of the family well) was not so much of Love but of extremes - if possible, for each of the girls, of love at the extremes. And often they found it: in communism or fascism (Jessica, Diana); in Hitler-worship (Unity); in a long, defining, but unreturned passion (Nancy).
Mary Lovell's portrait of the six sisters is full of information, and does well by the received account of these remarkable lives. She is thorough, kind, tactful, generous, even-handed; she is not judgmental. But she makes no allowance for this element of hyperbole. No leeway for the crafting of life, Scheherezade-like, into a wonderful, huge, story which dull truth should never be allowed to spoil (remember Linda in The Pursuit of Love, whose lover telephoned her every morning and said: "Alors, racontez" - even though he had seen her just hours before).
The book does not seem to understand the allure of the grand gesture, that essential motive. In these lives drawn in such broad strokes, lived out in "shrieks" of laughter and "floods" of tears, at social extremes, at opposite ends of the ideological spectrum, on opposing sides in war - to the extent that even Lord and Lady Redesdale's tough old marriage fell victim to such divisions - where did teasing end and real life begin? When Unity decided to shock her British society hosts by turning up to a weekend house party with a swastika pennant flying from her car; when she made a speech at Hesselberg for Julius Streicher - did she really see the difference?
Mary Lovell has no truck with any of this. She takes the sisters, and their stories, at face value. We find nothing here that is not available in other published sources - particularly The House of Mitford - and the sisters' story is now so well-known that it is perhaps time to look at it slightly differently.
But Mary Lovell is not interested in the wider context of these lives, or the social and political worlds they inhabited. Above all, she never questions the nature of memory, and the tricks it can play: nor how memory edited to avoid danger, or offence, or pain, can become truth. But it is a compelling story and she tells it well.
Jan Dalley is Literary Editor of the Financial Times. Her book, Diana Mosley: A Life, was published in 1999