Vinzenz Goller (9 March 1873 — 11 September 1953) A composer and organist.
This is described as a 'free canon' on the hymn Silent Night.
I played this three years ago on the Caen sampleset (http://www.contrebombarde.com/concerthall/music/23464
The score calls for Vox Humaine and Flute with tremolo to be played against a flute. I decided to go for the Bourdon and Regal with Tremolo. Hope you enjoy the heavenly sheep soloist...
Hope you enjoy.