"Stop the Cavalry" by Jona Lewie (sic) does mention Christmas DtG - it includes the line "Wish I was at home this Christmas" IIRC.

You must watch these points, as Jordan said to the Archbishop of Canterbury the other day.

As for In Dulci Jubilo, doesn't it mention Jesus, a prince, etc.? I can't remember the Latin lyrics though. But I agree Mike Oldfield's version doesn't mention it. :-)