Many of those "disappearing carols" were recorded in fine fashion by Nowell Sing We Clear, John Roberts (Mudcat's "Anglo"), Tony Barrand, Fred Breunig, and Andy Davis. They have retired from public performance, but their recordings will live on and on.
Here's a selection of their music:https://www.youtube.com/watch?v=4ERnwf7ilKY&list=PLy7uRohsU-RF9e0ErFZsNzw0B6IoyZxiG
Cheers!!
-Joe-