This is the final piece in the collection "Six Carol Preludes" and is a short Toccata. They were published by Oxford University Press in 1937 and are still available.
The tunes in this collection are found in the Oxford Book of Carols of 1928 and they are all treated in different ways. The melodies are still popular today with the exception of The Angel Gabriel which is now sung to a different tune.
Agnus Dei has uploaded the first of the collection here:
Here you will also find some informative notes on the composer.