Blakiston was born in London, the younger daughter of archivist"the most widely known archivist of his generation in England"and author Hugh Noel Blakiston (1905–1984), and (Rachel) Georgiana (1903–1995), daughter of barrister Harold John Hastings Russell (a descendant of the 6th Duke of Bedford) and Lady Victoria Alberta Leveson-Gower, whose father was the statesman Granville Leveson-Gower, 2nd Earl Granville. The Blakiston family originated in County Durham, and were related to the Blakiston baronets.Burke's Peerage, Baronetage and Knightage 107th edition, vol. 1, ed. Charles Mosley, Burke's Peerage Ltd, 2003, p. 320
