Nancy Mitford’s collected journalism does not deserve so misleading a title. She affected to believe, it is true, that the little jokes and teases of a prolonged childhood infuriated her readers the world over. But there is no need for us to swallow the myth. High-spirited, industrious and much-admired, Miss Mitford acquired under the tutelage of her friend Evelyn Waugh a style that was both easy and elegant. Her talent was not confined to mere mischief.

It is of course wearisome to plod once more through U and non-U: a vogue that for a generation banished such words as mirror, notepaper and mantelpiece from genteel vocabularies, even though Miss Mitford herself had used them freely in youth.

What justifies the resurrection of these threadbare themes is an ingenious idea of Charlotte Mosley’s: to preface each piece with extracts from Nancy Mitford’s correspondence.

‘It was wicked old Spencer, eye on sales, who egged me on to do the U stuff,’ Miss Mitford tells her mother, a few weeks after the publication of the article in Encounter. Who would have thought the Polonius of the Spanish Civil War, the cupbearer of Auden and Isherwood, capable of such guile? It is like finding Mr Pooter with his fingers in the petty cash.

And how refreshing to read Lady Redesdale’s dignified rebuke to her daughter after yet another oh-so-side-splitting chronicle of nursery life: ‘I wish only one thing, that you would exclude me from your books, I don’t mind what you write about me when I am dead, but do dislike to see my mad portrait while I am still alive.’

From the end of the war until her death in 1973, Nancy Mitford lived in France, first in Paris, then in Versailles. She loved France as the Windsors could never love it; she loved General de Gaulle; she loved his chef de cabinet, Gaston Palewski, who pinned on her the insignia of the Legion d’Honneur during her last and cruelly prolonged illness. Sometimes I would take her out to lunch and be rewarded by unusual insights into local life. ‘Every French boy of sixteen,’ she told me, ‘has shorts and a small moustache, a hoop and a mistress.’

The most striking pages of the present book are the Paris diaries she wrote for the Sunday Times when it was still a stylish and sophisticated newspaper. There are certain teases she could not resist. To refer to Daniel Cohn-Bandit, the revolutionary student leader, as Cohn-Bendit is more amusing the first time than the second, third and fourth. For the rest, she has caught the authentic flavour of Paris gossip: the theatre, fashion houses, etiquette, furniture, literary feuds and the Tour de France.

What treasures she has unearthed. Voltaire’s brain, left by mistake in a chest of drawers, is knocked down to the highest bidder at the Hotel Drouot. The railwayman who took in President Deschanel after he had fallen from a wagon lit in his pyjamas and knew it was someone important because his feet were so clean. No Frenchman uses the words blancmange or bon viveur in the dining room, or shouts encore at the opera.

One of her few complaints against the French is that their books rarely contain an index. Nor does this one: only ten blank pages where it should be. Miss Mitford does, after all, have a talent to annoy.