The first clear notice of his existence comes from his papal letter of provision to the bishopric of Dunblane dated 23 October 1347; in the letter Pope Clement VI complained about the election of William being made despite an earlier papal reservation of the see; Pope Clement declared the election null and void, before himself providing William to the see directly, ordering him to be consecrated by Cardinal John, Bishop of Porto.
[1] The same letter said that William had previously been a canon of the cathedral chapter of Dunblane.
[3] He was sent, along with three other bishops, on a diplomatic mission to England in early 1351 relating to a temporary release of the imprisoned Scottish king David II; he and the bishops of St Andrews, Aberdeen and Brechin met English officials at Hexham.
[4] He last occurs in contemporary sources in a charter of Inchaffray Abbey dated 11 April 1358.
[5] A 16th-century insertion in the Donibristle manuscript of Walter Bower's Scotichronicon stated that he died on 1 November 1361; this cannot be correct however, as contemporary sources testify that he had already died by 18 June, but the year is nevertheless probably reliable.