[From Burke' Peerage - see source for details]
John (King of England) prevented her (Isabel, youngest daughter of William FitzRobert) taking a second husband at all for the time being, however, and exchanged the Earldom of Gloucester with Aumarie de Montfort, son of William FitzRobert's eldest daughter Mabel, for the Comte of Evereux, which he then used as a dowry to secure the marriage of his niece Blanche with the King of France's son. Aumarie died childless.