Ian, just curious about what you mean by "the original version of Deck the Halls". Are you referring to the Mrs Opie words? The tune, Nos Galan (sometimes in English collections 'Nos Galen') is an old Welsh National Air but, if you're being true to the tradition, there are no 'original' words. It's a harp tune to which the Welsh would sing penillion - the trick being to sing whatever verses of appropriate metre and subjects the singer could come up with. The tune would certainly be old enough, but not Opie's words, if jennifer is looking for early Georgian. (And, of course, 'Deck the Halls' are latter half of the 19th century so not applicable.)

Anyway, it would 'work' if you, jennifer, are looking for instrumental pieces although I don't know how well known it would be in households without a Welsh connection (which would include houses visited by Welsh itinerant musicians).

"God rest ye merry g's" would sound nice, as Ian says. "I saw three ships" too perhaps?

sian