It's also an interesting example of a folk carol. I've said before that carols weren't originally intended to be sung in church (some were later written for it, once the others had started to become popular). In fact, they were rather looked down on by respectable society. Which is why I always feel they sound better sung with an earthy gusto rather than in the beautifully refined tones and perfect vowels of, say, Kings College, Cambridge.
There's a place for the latter, of course - and a very distinguished place at that. But a choirboy's fluting treble isn't all there is to a Christmas carol; in fact, it wasn't anything to do with it for many centuries. And it's nice to be reminded of that from time to time.
