Sarum Chant - Missa in Gallicantu
Chant for the First Mass of Christmas according to the Salisbury Rite. It would have been celebrated after midnight on Christmas Eve, and was known as the Missa in gallicantu - the Mass at Cockcrow. The chant has been taken from printed sources which would have been in use when composers such as Tallis and Tye were at the height of their powers.
These recordings are also available on Christmas with The Tallis Scholars, a specially-priced double album.