Trinity Sunday, is though a first class feast, and with some interesting additions of its own to the liturgy, including the recitation of the Athanasian Creed at Prime.
Accordingly, those saying the Office need to remember to drop all those stray alleluias, and return to the 'time throughout the year' rubrics.
In addition, at Compline, the Marian antiphon is, henceforth, Salve Regina.
Feasts this week
Sun 26 May Feast of the Most Holy Trinity, Class I
Mon 27 May St Bede the Venerable, Class III
Tues 28 May Class IV
Wed 29 May Class IV
Thur 30 May Corpus Christi, Class I
Fri 31 May Class IV
Sat 1 June Saturday of Our Lady