MITFORD MADNESS: After nearly 75 years, Penguin has reissued one of Nancy Mitford’s earliest novels, “Wigs on the Green,” and Tatler held a party at Claridge’s to mark the occasion. Guests including the Dowager Duchess of Devonshire, formerly Deborah Mitford, Nancy’s youngest sister; Tom Stoppard; Bella Freud; Susie Boyt, and Jasmine Guinness gathered to celebrate the social comedy that — among other things — pokes fun at Diana Mitford’s husband Oswald Mosley, founder of the British Union of Fascists. Charlotte Mosley, Diana’s daughter-in-law who has edited the Mitford sisters’ letters, penned the introduction to the book. Mosley said “Wigs” is by no means among Mitford’s best work. “She was still practising her scales,” she said, adding Mitford’s writing only really gained steam after she fell in love with Col. Gaston Palewski, the French soldier and politician.