Research Notes:
Keats-Rohan states, [1]
Ilbert de Laci
Norman, from Lassy, arr. Vire, cant. Condé-sur-Noireau, Calvados (Loyd, 53). Heir of his mother Emma, who was a nun of Saint-Armand de Rouen before 1069 (Cart. Saine-Trinité de Rouen, pp. 459-60); she was perhaps a daughter of Ilbert marshal (Fauroux, 104) and sister of Ingelran fitz Ilbert (Cart. Sainte-Trinité de Rouen, p. 466). He and his wife Hadruda were benefactors of Sainte-Trinité de Rouen, where their son Hugh was buried (charter printed in Arxhaelogical Journal iv, p. 249). Tenant-in-chief of a fief based upon Pontefract, Yorkshire in 1086, brother of Walter de lacy of Weobley (d. 1085), probably gained after the lands in Lincolnshire and elsewhere that he held of Odo of Bayeux. He founded the Collegiate Chapel of St Clements in his castle at Pontefract. He died c 1093/5, leaving his successor Robert I de lacy by his wife Havise (probably the same person as Hadruda above. It has been assumed that he was also rathr of Hugh, abbot of Selby, but there is no real evidence for this view. His son Robert confirmed a grant of land at Hamilton to Selby made by Ilbert 'pro anima fratris meo Hugonis; (Mon .Ang. iii, pp. 500-1). Since Ilbert is known to have had a son Hugh who died in his father;s lifetime it is very difficult to accept this 'pro anima' clause as a reference to s still living son who was a monk of Selby. See Wightman, Lacy Family, 26-45, 48-52, 55-8; Sanders, 138.
[1] K. S. B. Keats-Rohan, Domesday People, A Prosopography of persons occurring in English documents, 1066-1166 (Boydell & Brewer Ltd, 1999), 277, [GoogleBooks].