Holy orders
His part in ecclesiastical affairs was for a time also very important. For fully ten years he performed all the episcopal functions of the Church of Lyons, having been chosen for this work during the vacancy of the see by Philip I, Count of Savoy who, although not in Holy orders, bore the title of Archbishop of Lyon from 1245 to 1267. Because of Perault's long labours in ministering to the needs of the diocese, he himself came to be known as the Bishop or Archbishop of Lyon. This error was further emphasized by the title of bishop which a later hand added to many of his writings. Authors such as Gerson, Père Alexandre, Jacques Échard, and Hurter say that William Perault was never Archbishop of Lyons, as the "Gallia christiana" asserts, Dupin is not justified in saying that he was never more than a religious of the Order of Preachers (cf. Antoine Touron, "Hist. des hommes illust.," 1, l.2, 184).