Unusually Byrd has varied the scoring in this set of pieces. Two of them (Tu es pastor ovium and Quodcumque ligaveris) are scored for a divided low bass part whereas the others are for the more usual AATTBarB combination. This strongly suggests that they were written at different times rather than all composed for one occasion (perhaps Byrd was even writing for the singers whom he knew would be present). The angst of the 1591 pieces is banished in these settings where Byrd gives his imagination free rein. Perhaps he felt more comfortable in Essex away from London; perhaps he was feeling the wind of change blowing through the country as Elizabeth gave way to James VI of Scotland who had promised (but was never to deliver) greater toleration for Catholics. We will probably never know, but the remarkable fact is that Byrd even in his later years could produce the most modern-sounding and the most energetic music that he had ever written.
He provides only three pieces (Nunc scio vere, Constitues eos principes, and Tu es Petrus) for Mass itself. There is no Communion setting which is certainly unusual and he relies on the fact that the Alleluia verse Tu es Petrus has the same text as the Offertory and that the same music could be used twice (a common occurrence throughout the two books of Gradualia). The set is completed by the short Solve, iubente Deo and the beautiful Hodie Simon Petrus which, appropriately enough in a collection of texts which otherwise refer only to St Peter, reserves its most telling music for the mention of the death of St Paul.
from notes by Andrew Carwood © 2009