As a result of her 1st marriage, Lady Diana Spencer was styled as Viscountess Bolingbroke on 8 September 1757 and her married name became St. John. She held the office of Lady of the Bedchamber to Queen Charlotte between 1762 and 1768. From 12 March 1768, her married name became Beauclerk.
↑ Cokayne, G.E.; 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 II, page 207.
Virginia Surtees, ‘Beauclerk , Lady Diana (1734–1808)’, Oxford Dictionary of National Biography, Oxford University Press, 2004; online edn, Jan 2014 accessed 8 June 2017. This is a subscription site but access is free of charge to readers of British libraries whose library subscribes.