In about 1128, the Diocese of Whithorn was revived after three centuries had passed since the consecration of the last diocesan bishop. The revival itself is revealed by a papal mandate dated December 1128, and the record of the oath of the bishop-elect, Gilla Aldan, to Thurstan, Archbishop of York between about 1128 and 1140. It is uncertain who was the driving force behind the revival. David's known ecclesiastical activities could suggest that he was responsible. On the other hand, the extent of David's authority in Galloway is questionable. As for Fergus himself, there is no conclusive proof that he controlled the lordship at this point in time, or that he himself established the see.