Beck now gave up civil duties (except for some service in 1280-1 as royal commissioner in Wales), and henceforth was assiduous in his devotion to the interests of his church and diocese. His entry into the latter was made at the beginning of Feb. 1281, when he celebrated mass at Strata Florida. He was enthroned at S. Davids on 1 March. No part of the existing cathedral is attributed to him, but in other respects he showed much activity. In 1287 he strengthened the chapter by the creation of the offices of chancellor, subdean, and succentor. From the Crown he obtained for the episcopal lands the right of free warren, and for the urban centres therein fairs and markets on specified days. When archbishop Peckham, in the course of a tour of Wales, came to S. Davids on 10 July 1284, he entered a formal protest; this attempt to revive an old controversy did not get very far, for Beck was reminded that, at his consecration he had expressly recognized the supremacy of the see of Canterbury. On 26 Nov. 1284, the king and the queen visited their old friend in his cathedral city; it was a costly attention, for a little later he had to seek remission of a debt to the Crown to cover expenses incurred in this and other respects. The strong castle of Llawhaden, dominating the eastern Cleddau, is of this period and is believed to be his work. He founded two hospitals, one at Llawhaden and another, not far from the cathedral, at Whitwell. Lastly, mention should be made of two colleges which he established in remote parts of the diocese, the one in 1283 at Llangadock (afterwards moved to Abergwili), and the other in 1287 at Llanddewi Brefi.

Beck d. 20 April 1293, and was buried at S. Davids. The altar tomb in the north wall of the lady chapel is believed to be his. His career gives the impression of a simple devotion to duty; he was without the ambition and the aggressive temper of his more famous brother.