In 1769 the Adam brothers entered into discussion with the 2nd Duke of Portland regarding the development of Mansfield Street. The formation of this new street resulted in an odd 50 x 195 foot plot of land between Mansfield Street and General Clerk's house to the west, and Foley House and the newly envisaged Portland Place to the east. It was on this spare plot in 1769-71 that Robert and James Adam built a grand, speculative townhouse, with a magnificent view towards Cavendish Square (along what is now Chandos Street). A 99-year lease from 1767 was agreed in 1770, and James Adam took a mortgage on the property with Sir George Colebrooke, in order to facilitate the building works. The house was built in Craigleith stone, a material more commonly used by the Adam brothers in Edinburgh.

The only surviving Adam drawings for the fabric of Chandos House are ground and first floor plans in the Cumbria Record Office at Carlisle. It is a large townhouse, with a library and a private apartment on the ground and first floors of a rear wing, allowing the spaces on the ground and first floors of the main house to form a circuit of reception rooms. It has been widely noted by scholars since Bolton that this arrangement of a circuit of reception rooms anticipated the layout of other, grander London townhouses by Adam, such as 20 St James's Square for Sir Watkin Williams Wynn, and 23 (later 26) Grosvenor Square for the 12th Earl of Derby.

Drawings for the interior decorative schemes of the house are preserved at the Soane Museum, and these include Adam's ceiling designs for the eating room and parlour on the ground storey, the staircase, and the ante room and the first and second drawing rooms on the first storey. The work was complete in 1772, and in that year the house was placed for sale by auction with Christie's. No buyer was forthcoming, doubtless owing to the Scottish banking crisis, until 1774, when the remaining years on the lease were sold to James Brydges, 3rd Duke of Chandos (1731-89).

Prior to his succession in 1771, Chandos had served as MP for Winchester in 1754-61, and Radnorshire in 1761-68, as well as Lord of the Bedchamber in 1760-64, Lord Lieutenant of Hampshire in 1763-64 and 1771-80, and Lord Steward of the Household in 1783-89. He had only one surviving child, his daughter Ann Eliza, by his second marriage, and in 1796 she married Richard, Earl Temple (created 1st Duke of Buckingham and Chandos in 1822). Through this marriage, Temple inherited Chandos House on his mother-in-law's death in 1813. Two years later the lease was sold in 1815 to the Austrian Embassy, but on the expiration of the original lease in 1866, a new 99-year lease brought the house back into the Chandos family, when it was acquired by Ann Eliza Brydges' grandson, the 3rd Duke of Buckingham and Chandos.

The 3rd Duke made various alterations to the house, including the amalgamation of Adam's ground storey rooms in the rear wing to create a large new dining room. Moreover, Adam's friezes in the back parlour and drawing rooms were damaged at this time, and plaster moulded picture frames were affixed to the walls. When the 3rd Duke died in 1889, the lease passed to his nephew, the 4th Earl Temple. Temple died in 1902, and the lease then passed through various private hands, until 1963, when a new 99-year lease was acquired by the Royal Society of Medicine.

The Royal Society of Medicine sold their lease on Chandos House in 1986 in order to finance the refurbishment of their other building at 1 Wimpole Street. Unfortunately, the lease passed in 1990 to an investment company who left the house empty for five years, resulting in considerable damage. During this period many of the original chimneypieces were lost, the fabric developed large-scale dry rot, and Adam's ceilings were badly damaged by water ingress. English Heritage placed Chandos House on the buildings at risk register in 1994, issued a repairs notice to the leaseholders in February 1996, and a compulsory purchase order three months later. Chandos House was saved in 2002, when the Howard de Walden Estate (the freeholders) bought -out the leaseholders, and undertook a two-year programme of restoration works. In 2004 the house was leased, once again, to the Royal Society of Medicine, and now provides their hotel and conference facilities.

Literature:
A.T. Bolton, The architecture of Robert and James Adam, 1922, Volume II, pp. 48-53; Index pp. 36, 65; J. Lees-Milne, The age of Adam, 1947, pp. 120-21; Ralph Pay, Lord & Ransom, ‘Chandos House, Queen Anne Street', auction catalogue, 5th December 1963; D. Stillman, The decorative work of Robert Adam, 1966, p. 102; B. Weinreb, and C. Hibbert, The London encyclopaedia, 1983, p. 140; T. J. S. Draper, 'Chandos House', The Georgian Group Journal, 1997, pp. 130-39; D. King, The complete works of Robert & James Adam and unbuilt Adam, 2001, Volume I, pp. 18, 264, 270-71; A. Rowan, 'Bob the Roman': heroic antiquity & the architecture of Robert Adam, 2003, pp. 40, 59-60; E. Harris, The country houses of Robert Adam: from the archives of Country Life, 2007, pp. 151-55; 'Brydges, James, Mq. of Carnarvon (1731-89)', History of Parliament online

Frances Sands, 2013