This beautiful, haunting carol has no better interpreter than Ashley Davis. She's a Kansas musician who studied in Ireland to perfect her songwriting and vocals, which honor Celtic and other folk traditions. You can learn more about Ashley here, and download the album The Celtic Winter here. All her albums are marvelous.
The carol itself is a 17th-century English song. I love the melodic line and the juxtaposition of major and minor chords. Ashley's rendition perfectly captures the calm, cold spell that winter casts.