Ilbert de Lacy was probably born in Normandy no later than the year 1045, which would make him at least twenty-one years old in 1066. He was still alive in 1090 but had died by the end of the reign of William Rufus who was shot dead in a hunting accident in the year 1100.
That Ilbert and Walter were brothers seems probable as their land in Normandy was subsequently held jointly by their descendants under the Norman tenure of parage where land was divided amongst sons and daughters whilst remaining a single fee. This would mean that both Ilbert and Walter inherited the land from the same father. Their mother was named Emma de Lacy and there is a record of her granting 22 acres of land at Montmain to the nunnery of St Amand. She is described as the mother of Ilbert de Lacy to differentiate her from the abbess whose name was also Emma. This would seem to indicate that Ilbert was the elder of the brothers.
Ilbert and Walter held their lands in Lassy of Odo, bishop of Bayeax – the man responsible for the tapestry. After the Conquest Walter was rewarded with lands in Herefordshire and Gloucestershire and Ilbert received over 150 manors in the west of Yorkshire, ten in Nottinghamshire and four in Lincolnshire. Ilbert built a castle at Pontefract and enclosed it in a park that was eight miles in circumference and from here he administrated his new estates.
Ilbert was married to a woman named Hawise. They had at least two sons – Robert de Lacy who succeeded his father at Pontefract and Hugh de Lacy who died and was buried at La Trinite-du Mont in Rouen (the Abbey of the Holy Trinity) possibly around 1090 when Ilbert de Lacy and his wife granted their manor of Tingewick in Buckinghamshire to that abbey.
Charter of a Norman conqueror recording gift of the manor of Tingewick in Buckinghamshire to the abbey of La Sainte Trinite. Authenticated by the crosses, presumably autographs, of King William Rufus, Ilbert de Lacy, and Hawise, his wife. Ilbert’s seal is attached to the charter (the hole below Hawise’s cross). One of the earliest knightly seals in existence (c. 1090). The scribe is inconsistent in spacing, size of script, and spelling, suggesting lack of familiarity with this type of document. From Michael Clanchy, From Memory to Written Record: England 1066-1307. 2nd ed. Oxford: Blackwell, 1993, plate I.
Other grants made by Ilbert de Lacy were the manor of Hambleton to Selby Abbey (before 1997), the manor of Garforth to St Mary’s Abbey at York and a gift of two pence to Durham Cathedral priory. It is also probable that Ilbert granted permission for one or two hermits to live on land that later became Nostell Priory. He also made a grant to the chapel of St Clement, built within the walls of Pontefract Castle.
Exactly when Ilbert de Lacy died and where he is buried is unknown.