Portman Square was built at the edge of London from c1765 on land belonging to Henry William Portman. It suffered extensive bomb damage during the Second World War. Number 5 was the London home of the 6th Earl of Barrymore, being the central house on the east side of the square, which had been constructed in 1769-70 by a builder named Abraham Adams.

Richard Barrymore, 6th Earl of Barrymore (1745-73), succeeded his father aged six in 1751. He became an army officer, and a keen gambler, and in 1767 he married Lady Amelia Stanhope (died 1780), the 3rd daughter of William Stanhope, 2nd Earl of Harrington. He then took 5 Portman Square in 1770, immediately on its completion, and commissioned Robert Adam to make designs for an interior decorative scheme. The surviving drawings show ceiling designs for the reception rooms, and it is not known if further designs were made by Adam for other features of the interior, such as chimneypieces or furniture.

Adam's ceiling designs were not executed, and the Earl died in 1773, aged only 27, and was succeeded by his four year old son whose trustees did not retain 5 Portman Square.

Literature:
A.T. Bolton, The architecture of Robert and James Adam, 1922, Volume II, Index pp. 48, 62; B. Weinreb, and C. Hibbert, The London Encyclopaedia, 1983, p. 633; B. Cherry, and N. Pevsner, The buildings of England: London 3: north west, 1991, p. 650; D. King, The complete works of Robert & James Adam and unbuilt Adam, 2001, Volume II, p. 180

Frances Sands, 2013