Andrew and Waldron [ANDREW02] note that the adaption of the Beatitudes of St. Matthew at the start of Patience (l.9 ff.) is an adaption of the Use of Sarum, and is the gospel for the Feast of All Saints (1 November)

Philippa was responsible for the introduction of the Use of Sarum into the cathedral at Lisbon and into the royal chapel [RUSSELL01] (p.21).  James Cottrell would certainly have been just as familiar with the Sarum Missal as with the Roman version.