The Mitford family is a gentry (minor aristocratic) English family whose main family line had seats at Mitford, Northumberland. Several heads of the family served as High Sheriff of Northumberland. A junior line, with seats at Newton Park, Northumberland, and Exbury House, Hampshire, descends via the historian William Mitford (1744–1827) and were twice elevated to the British peerage, in 1802 and 1902, under the title Baron Redesdale. The Mitford sisters were William Mitford's great-great-great-granddaughters.
The sisters, six daughters of David Freeman-Mitford, 2nd Baron Redesdale, and Sydney Bowles, became celebrated, and at times scandalous, figures that were caricatured, according to The Times journalist Ben Macintyre, as "Diana the Fascist, Jessica the Communist, Unity the Hitler-lover; Nancy the Novelist; Deborah the Duchess and Pamela the unobtrusive poultry connoisseur".