The identity of Lady Innes has not been firmly established. Bolton has suggested a connection with Sir Ludovic Grant, Adam's patron at Moy House, who had married Margaret Innes (1703-82), the daughter of Sir James Innes of Belvery, 5th Baronet. Sir William Innes of Belvery, 6th Baronet (d1817), Margaret Innes's brother, married Sarah Hodges in 1770, and Sarah may be the Lady Innes in question. A plausible alternative is Mary Wray (d1807), who married Sir James Innes-Ker, 6th Baronet (1736-1823) in 1769, becoming another Lady Innes. Sir James Innes-Ker later became the 5th Duke of Roxburghe, and the owner of Floors Castle, and Roxburghe House in Hanover Square, for both of which Adam had previously made designs for the 3rd Duke.

A Mr William Innes subscribed to Adam's Ruins of the Palace of the Emperor Diocletian at Spalatro in Dalmatia (1764) but there is no known connection.

Literature:
A.T. Bolton, The architecture of Robert and James Adam, 1922, Volume II, Index pp. 55, 72; D. King, The complete works of Robert & James Adam and unbuilt Adam, 2001, Volume II, p. 122

Frances Sands, 2012