Through her daughter, Sibyl was the grandmother of Reginald fitzUrse, one of the murderers of Thomas Becket.
Sibyl was called the "nepta" (either "niece"[2] or "kinswoman"[1]) of King Henry I of England.
[2] The historian Frank Barlow also implies that she could have been Henry's daughter rather than his niece.
[6] Sibyl married Baldwin de Boulers (sometimes spelled Bullers),[2] at the instigation of Henry I.
[9] Matilda was the mother of Reginald fitzUrse, one of the murderers of Thomas Becket.