The diocese of St. Asaph extends into the counties of Flint and Montgomery, Merioneth, Denbigh, and Salop.
The archdeaconry of St. Asaph was coextensive with the limits of the diocese up to 31st Jan. 1844, and was always held by the bishop of this see in commendam, not union. On that day an order in council was made, directing that the dignity and office of Archdeacon of St. Asaph should no longer be holden by the bishop of St. Asaph; a second archdeaconry was at the same time erected, and called the Archdeaconry of Montgomery, and made to consist of the deaneries of Penllyn and Edeirnion, Pool and Caereinion, Caedewen and Ceifeiliog and Mowddy.
The chapter consists of the dean, two archdeacons, precentor, chancellor, treasurer, six prebendaries, seven cursal prebends, and four vicars choral.
Kentigern, bishop of Glasgow, having been expelled from his see, founded a monastery between the rivers Clwyd and Elwy, which during his lifetime was erected into an episcopal see, and he was styled Episcopus
- He was consecrated A. D. 540.