William is the second son, titular Earl of Derby since his elder brother was deprived of the earldom in 1265; - his mother gave him the manor of Groby in Liecestershire and he assumed the arms of the family of De Quincy (his maternal forebears). Burke's "Dormant Peerages" (1883, p. 198) states that he married 1st "Joane, dau. of Hugh le Despencer; and 2ndly, Eleanor, dau. of Matthew Lovaine" and that his two children were by Joane (William, his successor, and Anne [who m. John, Lord Grey of Wilton]); and reports that he died in 1288. Collins, "Royal Ancestors...," gives his death date as 20 Dec 1287.
bef 28 jan 1289 Eleanor second married Sir William Douglas, son of William Douglas (ca 1214/1420-ca 1276) & Lady Martha of Carrick. Born ca 1240. William died in 1298 in Tower of London.
William, the Hardy. While governor of Berwick he was captured when the town was besieged by the English and spent time in an English prison.