Byrhthelm was a supporter of Eadwig, and as soon as Edgar became king he reversed this act on the ground that Byrhthelm had not been able to even govern the Diocese of Wells properly. Edgar said that Byrhthelm was too gentle to maintain discipline, and he was replaced with Dunstan. He returned to Wells, where he served until he died on 15 May 973.
Byrhthelm initially backed Eadwig, but upon Edgar's ascension to the throne, he rescinded this support due to Byrhthelm's ineffectiveness in managing the Diocese of Wells. Edgar believed that Byrhthelm lacked the necessary firmness to maintain discipline and subsequently replaced him with Dunstan.