"When the producers of Bing Crosby’s “Merrie Olde Christmas” TV special asked Bowie to sing “The Little Drummer Boy” with Bing in 1977, he flatly refused. Ian Fraser, Buz Kohan and Larry Grossman left the set and found a piano in the studios’ basement. In about 75 minutes, they wrote “Peace on Earth,” an original tune, and worked out an arrangement that weaved together the two songs. Bowie and Crosby nailed the performance with less than an hour of rehearsal. Bowie liked it."
Found Here: The Selvedge Yard