Roger de St. John had a daughter Muriel, who m. an Orval and was the mother of Mabel, wife of Adam de Port of Basing, through whom both St-Jean-le-Thomas and the manor of Halnaker passed to that family. [Complete Peerage XI:342]
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Since the wife of Robert de la Haie was named Muriel and they were the parents of Cecily, Roger de St. John's wife, it is quite likely that Roger's daughter should have been named after her, and on this point one seems justified in accepting the statement of the "Historia". [Complete Peerage XI:320 note "f"]