From Richard Runciman Terry's 1912 Twelve Christmas Carols. He writes that the aim was to use 'old traditional carols' - the words of which were 14th century, and to have 'folk' type music rather than 'hymn' type music.
I play four pieces here:
So blyssid be the Tyme
The King's birthday
The Angel Gabriel
When Christ was Born.
The book can be found here: https://imslp.org/wiki/12_Christmas_Carols_(Terry%2C_Richard_Runciman
I'm no carol, folk or 14th century music expert, so the registrations are simple and what sounded best to my ears (they are all variations of the same registration though).
Hope you enjoy