Background
He was the younger son of Charles Stourton (1669–1739), third son of William Stourton, 12th Baron Stourton. He was the younger brother and heir of Charles Stourton, 15th Baron Stourton (1702–1753). William"s mother was Katherine Frompton (d 1736).
William was the second of five children, with one elder brother and three younger sisters.
Mary (1706–1764), Jane (1708–1769) and Katherine (1710–1777).