Nothing is known about bishops in the post-Roman British Kingdom of Cornwall, but by the mid-ninth century Wessex was gaining control over the area, and between 833 and 870 a bishop at Dinuurrin, probably Bodmin, acknowledged the authority of the Archbishop of Canterbury.
[1] By the end of the century Cornwall was part of the diocese of Sherborne, and Asser may have been appointed the suffragan bishop of Devon and Cornwall around 890 before he became bishop of the whole diocese.
[2] When he died in 909, Sherborne was divided into three dioceses, of which Devon and Cornwall were one.
In Æthelstan's reign (924-939) there was a further division with the establishment of a separate Cornish diocese based at St Germans.
In 1050, the bishoprics of Crediton and of Cornwall were merged and the Episcopal see was transferred to Exeter.