 Part of the difficulty with establishing his biography is that he has previously been conflated with various other 13th-century Englishmen named William, such as William of Leicester (d. 1213) and William of Durham (d. 1249) (cf. Grabmann 1937, pp. 11–13; Kretzmann 1966, p. 3; Mullinger 1873, p. 177). He has also sometimes been identified with others bearing the same surname, such as the author of commentary, now lost, on the Sentences of Peter Lombard with the title Shirovodus super sententias, a work that was known to John Leland in the 16th century (Kretzmann 1966, p. 12), or Ricardus de Schirewode, who wrote a treatise on insolubles surviving in Cambridge, St John’s MS 100. This confusion, along with the usual problems presented by anonymous material, makes it difficult to identify William’s works with certainty.