Eustace de Vescy was the son of William de Vescy (d.1183) and Burga, daughter of Robert (III) de Stuteville, lord of Cottingham. He reached his majority in 1190, at which time he inherited lands in Yorkshire and Northumberland. He was lord of Alnwick (Northumberland) and married Margaret, an illegitimate daughter of King William I. With her he had one son, his heir, William (d.1253). Eustace died in August 1216, when he and Alexander II laid siege to Barnard Castle, which belonged to Hugh de Balliol. http://www.oxforddnb.com/view/article/28253