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.
Tanner, `Reassessing King Stephen's continental strategies', aims to demonstrate that ill fortune, not lack of political or military skill, accounted for Stephen's failure to consolidate his hold on the English throne during his war with Matilda and Geoffrey Plantagenet