Ellis shows the supposed brothers in his genealogical table as born from different mothers.Presumably he bases this on Emma naming only her son Ilbert in the charter which is quoted above.The problem of the precise parentage of Gilbert de Lacy, probably identified as the unnamed nepos shown below, is discussed in more detail later.] (-[May 1160/1163]).His co-identity with the unnamed nepos of Hugh de Lacy is indicated by the charter dated May 1160, which records a treaty between Louis VII King of France and King Henry II, subscribed by "Willelmo Pavet magistro Templi et fratribus... The precise date when Gilbert joined the Knights Templar has not been ascertained.The difficulty is that Sibyllas descendants inherited only part of the Lacy estates, as indicated by the charter dated to [Dec 1137/May 1138] under which King Stephen only referred to Sibyllas dowry as quoted below, whereas Sibylla would presumably have been sole heiress if Hugh had been her father.Rivalry between Sibyllas heirs and Gilbert de Lacy (see above) concerning the succession to the Lacy estates in England is indicated by an agreement dated to [1147/49] between Roger Earl of Hereford (husband of Sibyllas older daughter) and William Earl of Gloucester to combine forces against Gilbert de Lacy.Orderic Vitalis records that King William granted insulam Vectam et comitatum Herfordensem to Willelmo dapifero Normanni Osberni filio, and sent him cum Gualterio de Laceio to fight contra Britones [Welsh], during which they first invaded Brachaniaunos and defeated Guallorum reges Risen et Caducan ac Mariadoth, dated to 1071.The Historia sancti Petri Gloucestri records the death "VI Kal Apr" 1085 of "Walterus fundator Sancti Petri Hereford", his burial "Gloucestri in capitulo", and the donation of "villam quinque hidarum Duntesborne tempore Serlonis abbatis" [abbot from 1072 to 1104] made by "uxor eius Ermelina"The Historia sancti Petri Gloucestri records the death "VI Kal Apr" 1085 of "Walterus fundator Sancti Petri Hereford", his burial "Gloucestri in capitulo", and the donation of "villam quinque hidarum Duntesborne tempore Serlonis abbatis" [abbot from 1072 to 1104] made by "uxor eius Ermelina".
From a chronological point of view, the two marriages would fit.
Ellis suggests that Walter de Lacy was the brother of Ilbert de Lacy, highlighting that Walter held a "knights fee in Lassy and Campeaux" in Normandy from Odo Bishop of Bayeux and that "this fief was afterwards held in parage by the heirs of Walter and Ilbert" .
The Historia sancti Petri Gloucestri records that "Helewysa relicta Willelmi de Ebroys" donated "terram Hyda, quam Walterus de Lacy dedit ei in matrimonium" with the consent of "rege Henrico senioretempore Willelmi abbatis" [abbot from 1113 to 1131].
He must therefore have reached the age of majority at his fathers death.
Florence of Worcester names "Beornardus de Novo Mercatu, Rogerius de Laceio Rawlfus de Mortuo Maricum hominibus comitis Rogeri de Scrobbesbyria" threatened Worcester with an army of Normans and Welsh, dated to .