Although the dedication of the cathedral church to Deiniol is undisputed, there is no direct evidence for the dedication of the church prior to the eighteenth century. However, the poem by Syr Dafydd Trefor, in praise of Deiniol at the time of the renovation of both the church and bishop’s palace in Bangor under the patronage of the bishop, Thomas Skevington, clearly indicates the importance of the saint there in the 1520s.