He was born Archibald James Edward Stewart, in Paris,G.E. Cokayne; with Vicary Gibbs, H.A. Doubleday, Geoffrey H. White, Duncan Warrand and Lord Howard de Walden, editors, The Complete Peerage of England, Scotland, Ireland, Great Britain and the United Kingdom, Extant, Extinct or Dormant, new ed., 13 volumes in 14 (1910-1959; reprint in 6 volumes, Gloucester, U.K.: Alan Sutton Publishing, 2000), volume IV, page 441. the twin son of Sir John Stewart, 3rd Baronet (1687–1764) and Lady Jane Douglas, daughter of James Douglas, 2nd Marquess of Douglas. The circumstances of the birth were controversial. His mother was the sister of the wealthy Duke of Douglas. As the Duke was childless, his estate would pass to the next in line, the Duke of Hamilton, unless an heir could be found. Lady Jane was 47 when she married the 60-year-old Colonel John Stewart, a man described by her brother, the Duke of Douglas, as a 'wore-out old rake'. In the summer of 1748, by which time she was 50, Lady Jane gave birth to twin boys - Archibald and Sholto - at the house of Madame Le Brun in Faubourg Saint-Germain, Paris.
