The influence of Thomas Tallis is clear in this setting of the Dorian mode plainsong. The text of the chant is Gloria tibi trinitas equalis una deitas et ante omnia secula et nunc et in perpetuum
(‘Glory be to you, Trinity, one equal Godhead, from before all centuries, now and for ever’), the Sarum rite antiphon to the Psalm Laudate pueri
at Vespers on Trinity Sunday. It is undoubtedly one of Byrd’s earliest pieces, and includes what appears to be a deliberate quotation from Tallis’s own setting of the same plainsong. Byrd, as did his mentor, uses the cantus fractus technique described above in the note to his first Miserere
setting (BK66). The highly ornamented left hand is built out of the plainsong, which ends up being quite unrecognisable. The appearance of an additional voice in the last few bars is typical of Byrd’s plainsong settings for keyboard. The work is played here at 5’ pitch.
from notes by Davitt Moroney © 1999