John William Clayton, a member of that noble English house, succeeded his elder brother Cecil Arthur as Duke of Greystoke in 1765 at the age of fifteen, a few short months after the first Duke himself died of a fall from a horse. His life is briefly discussed by Philip José Farmer in Tarzan Alive.
The Duke married Alicia Rutherford, and together had two sons - Sir Jesse Clayton, 4th Duke of Greystoke and the celebrated General Sir William Clayton - through whom they are the ancestors of many distinguished people, most obviously Tarzan of the Apes.
The Duke and Duchess were witness to the Wold Newton Meteorite strike in 1795, at which time the Duchess of Greystoke was pregnant. The Duke and Duchess were lost at sea in early 1801, and presumed dead.