Question: What is the date of death of William Fitz Robert, 2Nd Earl Of Gloucester's mother?
Sentence (from "Mabel FitzRobert, Countess of Gloucester"): Mabel FitzRobert, Countess of Gloucester (c. 1100 – 29 September 1157) was an Anglo-Norman noblewoman, and a wealthy heiress who brought the lordship of Gloucester, among other prestigious honours to her husband, Robert, 1st Earl of Gloucester upon their marriage.
Relevant evidence: Yes