William FitzRobert 2nd Earl of GLOUCESTER

                   [From Burke' Peerage - see source for details]

John (King of England) prevented her (Isabel, youngest daughter ofWilliam FitzRobert) taking a second husband at all for the time being,however, and exchanged the Earldom of Gloucester with Aumarie deMontfort, son of William FitzRobert's eldest daughter Mabel, for theComte of Evereux, which he then used as a dowry to secure the marriage ofhis niece Blanche with the King of France's son.  Aumarie died childless.
                  

                   [From Burke's Peerage-see source for details]

An undoubted Earl of Gloucester, perhaps the first authentic one, at anyrate after the Conquest, is Robert FitzHamon's son-in-law, anotherRobert, who was an illegitimate son of Henry I and was so created 1122.The Earldom passed to his eldest son, William FitzRobert, and from him toJohn, later King John and husband from 1189 to 1199 (when he divorcedher) of Isabel, the youngest of William FitzRobert's three daughters.  OnJohn's coming to the throne the title did not merge in the Crown for itwas not his in his own right but in right of his wife.

Isabel's situation now became that of a great heiress, for whoever shemarried next would gain the Earldom.  John prevented her taking a secondhusband at all for the time being, however, and exchanged the Earldom ofGloucester with Aumarie de Montfort, son of William FitzRobert's eldestdaughter Mabel, for the Comte of Evereux, which he then used as a dowryto secure the marriage of his niece Blanche with the King of France'sson.  Aumarie died childless and Isabel, who towards the end of John'sreign married as her second husband Geoffrey de Mandeville, Earl of Essexand in right of his new wife now Earl of Gloucester too, died childlessafter marrying in the autumn of 1217 yet a third husband, Hubert deBurgh, Earl of Kent.

The latter seems not to have been recognised as Earl of Gloucester aswell as of Kent, despite his wife's undoubted possession of the formerEarldom by the time of their marriage.  But then she died only a few dayslater and her sister Amice, by now the only one of William FitzRobert'sdaughters still living, seems to have been recognised as Countess ofGloucester till her own death some seven and a half years later.  On theother hand Amice's son Gilbert de Clare, Earl of Hertford or of Clare(usually called the latter), was apparently acknowledged as Earl ofGloucester in addition to his other dignity from as soon as the monthafter his aunt Isabel's death back in 1217.