Another from the chorus (the same line up listed for Hark Hark), that Jon introduces by informing us that “There are something like fourteen different versions of While Shepherds Watched sung around Sheffield. We’ll not be doing them all but maybe a few. It is a great lyric – so familiar that you don’t really notice it, but kind of perfect as a Christmas lyric.” I found this in my searches
The carol While Shepherds Watched dates back to 1703. The words for While shepherds watched were written by Nahum Tate and Nicholas Brody. Only the Psalms Of David were sung in the Anglican Church prior to that time. The familiar melody used for While Shepherds Watched was taken from Siroe, an opera by George Frederick Handel.
Wiki expands on that and perhaps casts doubts as to the date claimed, but only by a year or three. As Jon has indicated there are many different versions of the tune for this, but I believe the lyrics remain fairly constant and for that Tate, the Poet Laureate in the reign of Queen Anne, takes the credit. Unusually I’ve also found a copy of the score, which I link to as it seems to suggest Pentonville was written by William Marsh (c1780-1805.) You might also care to have a look at this giving a very brief overview of hymns in general.
You can buy the December digital album now from all good download stores: