The Ultimate Christmas Song?

Claire has challenged me with finding the ULTIMATE Christmas song.  This seemingly impossible task has already been made difficult by most of the best one's being picked already, including Claire's own choice of Last Christmas and Sian's choice of All I Want For Christmas.

For me, there's only one choice.  I can name it from the first note in true "Name That Tune" style and can name every single person, in order, when not watching the video.  I received the single (yeah, kids, a 'single', remember those?) as one of my Christmas presents in 1984 and I had the 'behind the scenes' programme (Boy George turning up pissed, an atmosphere you could cut with a knife, Status Quo cutting something else with a knife or a credit card...) on video somewhere but it's long gone. *sad face*

And the lyrics... hastily written but very clever.  Maybe it's the nostalgia kicking in but there is no cover that has come close to the quality of the original (not even the version shown on Glee the other night with everyone all happy clappy and cheesy grins - wrong sentiment for the song, in my opinion).

So, what is your ultimate Christmas song?