While in office as bishop, St-Calais gave a copy of the "False Decretals" to his cathedral library. The manuscript was an edition that had been collected or prepared by Lanfranc for the use of the chapter of Canterbury. St-Calais may have used this copy in his trial. His plea for an appeal to Rome was grounded in the "False Decretals", whether or not it was based on this particular manuscript. The manuscript itself is now in the Peterhouse Library. St-Calais also gave a copy of Bede's "Historia ecclesiastica gentis Anglorum" to his cathedral chapter; this copy still survives. Other works that St-Calais gave to the cathedral library were copies of Augustine of Hippo's "De Civitae Dei" and "Confessions"; Gregory the Great's "Pastoral Care", "Moralia", and "Homilies"; and Ambrose's "De Poenitentia".