Mathilde was the daughter of unknown parents. The date and place of her birth have not been found.
Her husband was Brian FitzCount. They were married, but the date and place have not been found. They had no known children.
Note 1
Elle serait veuve de Miles Crespin et fille et héritière de Robert d'Oilly de Wallingford ou fille de Miles Crespin et Maude d'Oilly.