- Ducal Chancellor of the Privy Seal of John of Gaunt, Duke of Lancaster, 1383-1400.
- Sent to the Curia, on behalf of the duke, asking the Pope to confirm the dispensations requested by King John I of Portugal, revoking his vow of celibacy as a former Master of the Military Order of Avis, and confirming the legitimacy of his marriage to the duke's daughter, Philippa. [João2, ch. 123]
- Bibl: Edward Baines, History of the County Palatine and Duchy of Lancaster: I, Volume 1, (London, Paris, New York: Fisher & Son, 1836), p. 182
Guilhelm, doutor em lex