Within the last few months I happened upon a YT video by Pannonia featuring Thomas Tallis', "Sermone Blando Angelus". Looking for a chant rendition that he based his music on I can't find the same melody, which I think is a shame since the current one on gregobase is different/repurposed...Perhaps I'm wrong but the simpler melody actually sticks and I can see why other contemporaries of T.T. used it.
Am I missing something on why we no longer use the older plainsong?