The town house of the Dukes of Devonshire, built about 1737 by the third Duke who was satirised by Pope) on the site of an older edifice of the same name, was designed by Kent, and cost upwards of £20,000. It contains, besides a collection of gems, many fine paintings by old masters, and the unique collection of old English plays formed by John Philip Kemble. Devonshire House was long the headquarters of the Whig party, and here Georgiana, the beautiful Duchess whose enthusiasm for Fox is a matter of history, held her brilliant court. The house stands back from Piccadilly between Berkeley Street and Stratton Street, and has a spacious garden in the rear.
source: The Queen's London : a Pictorial and Descriptive Record of the Streets, Buildings, Parks and Scenery of the Great Metropolis, 1896