It is traditional English, and a "general" carol, as it also has allusions to the Passion. The earliest known version of the words (and I am sitting with the Oxford Book of Carols on my knee) apparently goes back to c.1500 and has references to a stone with Corpus Christi written on it, so it is also Eucharistic. The refrain is different too. If you want the carol for Christmas, the last verse of the Castleton version (starred for ommission at other times of the year) is:

Over that bed the moon shines bright Denoting our Saviour was born this night:

I have loved this carol for many years.

mouldy