Why he doesn't pronounce is or as that way for consistency is beyond me.
One MIGHT be able to make the case that in a historical performance setting, one should pronounce the words the way they would have been pronounced when the piece was composed. But even that, I think, is a bit of a stretch: Should we Anglicize the Latin pronunciation of Byrd's Masses? Should Coverdale be prayed according to pirate-sounding Original Pronunciation?
The so-called English cathedral choral tradition is a living thing, not just an historical artifact.
The correct pronunciation is that taught by your choirmaster.
To participate in the discussions on Catholic church music, sign in or register as a forum member, The forum is a project of the Church Music Association of America.