William Byrd's Gradualia is a collection of polyphonic Mass propers and related pieces, 109 items in all, covering the major feast days of the Roman liturgy as well as a number of votive Masses and miscellanea. Byrd published it in two volumes, the first in 1605 and the second in 1607. The ink was barely dry on Gradualia I when the Gunpowder Plot was revealed, an event which understandably soured the English market for Catholic books. Gradualia II appeared some eighteen months later, with a pointed remark in the dedicatory preface that these pieces had been ‘long since completed by me and given to the press’ (iamdudum a me peractas, ac Prelo commissas) – the unspoken complaint being that Byrd was either forced to delay publication in self-defence or held off by a nervous printer.