Yet another version - we used to sing:
While shepherds washed their socks by night
All seated round the tub
The angel of the Lord came down
And they began to scrub.

Not forgetting:
Good King Wenceslas knocked a bobby senseless
Right through Woolworth's window.
Up came a copper with a rusty gun
"Right, you beggar, I'll make you run"

Wassail! V