In the early 1770s Robert Adam had intended Portland Place to be a broad, enclosed space populated by speculative, large-scale, individual mansions - a 'Strada di Palazzi' as Bolton calls it. Unfortunately prospective patrons such as the Lords Kerry and Findlater were discouraged towards the middle of the decade by the financial downturn caused by the American War of Independence. Towards the end of the decade, however, interested patrons returned. Presumably Robert was occupied elsewhere, or was exasperated with the scheme, as according to his obituary in the Gentleman's Magazine, James Adam was responsible for the much less grandiose executed scheme of sixty-eight terraced houses divided into blocks by the side streets. The work was completed in the year of James's death (1794), though two of the houses were still unoccupied at this time.

In 1783 Mrs Cornwall lived at number 66 Portland Place. There are no extant drawings for the fabric of the house, but there is one design for a chimneypiece and overmantel mirror frame. Bolton suggests that James Adam might have been responsible for this design, presumably because of his responsibility for the fabric of Portland Place.

Demolition in the 1910s, 1920s and 1930s, followed by considerable war damage 'totally destroyed the homogeneity of the original'. All of the surviving Adam houses in Portland Place have been altered, and thirty-four have been replaced, including number 66, which is now the headquarters of the Royal Institute of British Architects (1932 -34) by Grey Wornum (1888-1957).

Literature:
A. T. Bolton, The architecture of Robert and James Adam, 1922, Volume II, pp. 102-111, Index p. 45; E. Harris, The furniture of Robert Adam, 1963, p. 57; D. Yarwood, Robert Adam, 1970, pp. 164-65;B. Cherry, and N. Pevsner, The buildings of England: London 3: North West, 1991, pp. 647-48; B. Weinreb, and C. Hibbert, The London encyclopaedia, 1993, p. 633; D. King, The complete works of Robert & James Adam and unbuilt Adam, 2001, Volume I, pp. 86-94

Frances Sands, 2011