I believe in Father Christmas: Greg Lake. One more for the holiday!
Recorded by Lake of Emerson Lake and Palmer in 1975, it was his biggest solo hit.
The original video, shot partly in the Sinai desert and Qumran in the West Bank, also contains shots of the Vietnam War, leading to complaints that it should not be shown with light-hearted Christmas songs (the lyrics are certainly not light hearted, though!). These images of war are a violent backdrop to a peaceful-sounding song and create a hard-hitting message. Unfortunately those scenes are missing in this version, evidently sanitized away..you can find them on other YouTube versions (I picked this for best sound quality).
Wiki: “The instrumental riff between verses comes from the “Troika” portion of Sergei Prokofiev’s Lieutenant Kijé Suite written for a 1934 Soviet film, Lieutenant Kijé.”
For all ELP and prog rock fans, including David Haddad , who mentioned this song as a favorite.