[1] His father, the 1st Earl, was one of the Conqueror's most trusted and most rewarded barons who, at his death in 1088, was the third- or fourth-richest magnate in England.

[2] In 1088 William II inherited his father's lands in England and his Norman estates including the castles of Mortemer and Bellencombre in Haute-Normandy.

[1][10] After the king's death disturbances broke out in Normandy and William was sent to guard Rouen and the Pays de Caux.

[12][13] William's death is recorded as 11 May 1138 in the register of Lewes Priory and he was buried at his father's feet at the chapter house there.

[16] She was a daughter of Hugh I, Count of Vermandois and granddaughter of Henry I, King of France, as well as the widow of Robert de Beaumont, 1st Earl of Leicester.