The See of Canterbury seems, at this time, to have been passing through a period of comparative obscurity; for during the nine years of the pontificate of Deusdedit, all the new English Bishops, with one exception, were consecrated by Celtic or foreign Bishops. Deusdedit, however, did found a nunnery in the Isle of Thanet and had some share in the foundation of Medshamstead Abbey (Peterborough Cathedral) in AD 657.

The Synod of Whitby which debated whether the Northumbrian Church should follow the Roman or Celtic Irish Church was held in AD 664. Due to his affliction with the plague, Deusdedit does not appear to have been present for the victorious Romanist party and his death took place on 14th July, only a few months later.