Joe is quite right to be puzzled by the adoption of this song as one of the pivotal carols of the Christmas season in the villages of South Yorkshire and Derbyshire as on the surface there is nothing seasonal whatsoever about the song. The clue I think lies in the glorious tune by James Leach, which is very strongly related to the music for other more obviously seasonal carols, not least with the exciting bass parts.
Apart from the excellence of the tune, another element which goes to ensure the continuing popularity of the song as a pub carol, and which probably also led to its expulsion from the Primitive Methodist Hymn Book, is the final line:-
"Come drink and thirst no more."
Anyone who has ever heard the vigourous enthusiasm with which this line is repeated in the crowded front room of the Royal in Dungworth, will be under no illusion but that this is 'really' a drinking song thinly disguised as a hymn!

Matthew