Look at it too closely, and it breaks down into the cold destructiveness of snobbery. Accept it, and it is a wonderful fantasy, rich in escapist possibilities. Accept, for a start, the absolute glamour of the set of Mitford sisters, who seemed able to write their own destinies in their childhood and never deviate from them: Diana, the beauty; Unity, the fascist who became an intimate of Hitler's; Nancy, the writer; Jessica, the communist who ran away to the Spanish Civil War; Deborah, the Duchess; and Pamela, who 'wanted to be a horse'.
If you know anything about them, from their memoirs, or from Nancy's best-loved and most autobiographical works, The Pursuit of Love and Love in a Cold Climate, reading these letters is like revisiting a comfortable, well-worn house. We go to a miserable refugee camp for Spaniards in 1939, and meet the British playboys turned relief workers, just as Linda did in The Pursuit of Love; we hear of Jessica amusing children of the neighbourhood with tales of how babies are born, just as in Hons and Rebels; we meet the glamorous ex- ambassadress to Paris, just as in Don't Tell Alfred, only here she is called Lady Diana Cooper.
Its familiarity doesn't make it, necessarily, a comfortable world. In her novels Nancy mastered her life, making everyone who was different or difficult into figures of mirth, moving only among the aristocracy, and infusing the world with a spirit of lazy, delightful romance. In The Pursuit of Love, particularly, Linda wanders from adolescent infatuation with a rich banker, to a brief interlude with the idealistic Christian, to true love in Paris with Fabrice, Duc de Sauveterre.
Nancy was quite happy for much of this to be taken as autobiography, often referrring to her own French lover as Fabrice, and writing: 'Everybody seems to think every word literally of the book is true. Nancy Cunard is here and Victor said to me 'she gives a much more gloomy account of Paris than you do, but then of course nobody took a flat for her or gave her all those fur coats.' '
Unfortunately, nobody did that for Nancy either. She went from an unrequited love for a homosexual, Hamish St Clair-Erskine, which engagement was viciously broken off; to a disastrous marriage with Peter Rodd, who was incapable of providing any security or love; to a life-long adoration of Gaston Palewski. Although they were sexual and intellectual companions, he never married Nancy, and in fact told her about his impending marriage to another, richer and younger, woman at about the same time as she discovered she had cancer, when she was 64.
Despite all the elegant brio of her style, Nancy's letters reflect her deep dissatisfaction with the unyielding stuff of reality. Real arguments crop up with her fanatically political sisters and her hazy, unloving mother; financial crises as her husband spent his way through her earnings; despair over her failed love affairs; even a couple of suicide attempts are mentioned, all shockingly harsh to those of us accustomed to her bubbling fiction.
But despite the endless struggle between fantasy and hard knocks, this volume of letters has the smooth shape and emotional crescendo of a fictional work. Nancy's early letters, like her early books, are excessively childish, steeped in the slang and party culture of the Twenties. Her mature letters, like the books of her mature years, are a delight, full of the sparks of an abrasive and entertaining wit, refreshingly free from politeness. 'Peter Brook said R Morley's great fault is he is so disloyal & I replied well I'm very disloyal myself so it's not a thing I ever mind at all,' she once wrote, and, refusing to see a friend who had annoyed her: 'You haven't given offence, you have given an excuse.'
Nancy suffered nearly five years of constant agony before her death in 1973, but her last letters reach a piquancy, in which the practised wit fights with a true depth of emotion, that is bettered nowhere else in her work. Who but Nancy Mitford could write on her deathbed: 'It's very curious, dying, and would have many a drole amusing & charming side were it not for the pain . . .' As Pascal said, the last act is always bloody, no matter how charming the rest of the play. But Nancy Mitford kept up the charm through all the bloodiness. Her final letter, a gut-wrenching scream of pain addressed to Palewski, ends with a last wave of elegant generosity: 'Hassan (her servant) has been too wonderful.'