Sybilla Corbet noblewoman and royal mistress (1077–1157) Parents NN Robert Corbet, Earl of Cornwall Children Robert, 1st Earl of Gloucester Sybilla of Normandy Reginald de Dunstanville, 1st Earl of Cornwall William, Constable Herbert FitzHerbert Rohese (?) Gundred (?) Partners Henry I of England Herbert FitzHerbert