Also available in Carols for Choirs 3 and 100 Carols for Choirs.
The accompaniments for orchestra and brass ensemble are available to hire at the OUP link below.
There is a separate arrangement in 6/8 time, with its own orchestral accompaniment, only in Eight Christmas Carols: Set 2.
Orchestration: Brass ensemble: 4 tpt, 3 tbn, tuba, perc, hp (opt) Chamber orchestra: 2.2.2.2-2.0.0.0-timp.perc-hp-str