In AD 930 Athelstan, a Saxon King who came west to drive out the Danes, took communion in Saint Buriana's Oratory before crossing to the Isles of Scilly. He vowed that, if he won his battle against the Danes on the islands, he would build and endow a church on the site of Buriana's oratory as a thanks offering.
On his return he fulfilled his vow and ordered a church to be built. This King's free church, a Royal Peculiar (a place of worship that falls directly under the jurisdiction of the British monarch, rather than a diocese), consisted of Canons Augustine or regular priests, and three prebendaries who might enjoy the revenues but must not marry.
Athelstan's charter (dated October 6th 932) and founding are partly confirmed by 1086 in the Domesday Book; This records that The Canons of St Berriona hold Eglosberrie and that before 1086 it was free from "payment of geld".