Pope Gregory the Great sent Augustine to establish an organized Church in England (597), resulting in the foundation of the sees of Canterbury, Rochester and London. Later, the Irish missionary Aidan founded Lindisfarne (635), from whence the monk and bishop Cedd established a see for the East Saxons at Bradwell (653). Dorchester and Winchester had already been instituted by the time of the Synod of Whitby (664), which secured the future dominance of the Roman Church over the competing Celtic tradition. Theodore of Tarsus, Archbishop of Canterbury (669–90) initiated a vigorous programme of diocese creation: East Anglia was divided between Dunwich and Elmham, a new Wessex see was established at Winchester, and Mercia and its hinterland was served by dioceses based at Lichfield, Lindsey, Leicester, Worcester and Hereford. In the early 8th century, Winchester was subdivided, creating the new sees of Selsey and Sherborne, while York was made a second archbishopric (735), completing the eclipse of Lindisfarne.
— OR —