In the meantime, he was strengthening his own faction in the kingdom, of which he proposed to dispute the succession, in case of the King's death, with the legitimate heir, Arthur Duke of Brittany, son of Geoffrey Plantagenet
, the elder brother of John.
In the mid-1140s he entered the service of Archbishop Theobald of Canterbury, moving in 1159 to the household of Roger, Archbishop of York, until the latter's death in 1181, and remaining under Geoffrey Plantagenet
until his own death in about 1200.
Among the Anglo-Norman aristocracy there were many who saw Henry as an outsider: an Angevin princeling, descended via his father, Count Geoffrey Plantagenet
of Anjou, from a dynasty that had long been regarded as the principal rival on Normandy's southern frontier.
He had made his barons recognise as his heir his daughter Matilda, wife of Geoffrey Plantagenet
, Count of Anjou.