Dug the book back out in response to my original post.

Book states;

" From William Topliss's 'Melodies Of the Tyne and Wear', published over 50 years ago. This song, or one nearly identical, was also formerly common to the mummers of North Yorkshire at Christmas time. the person who sung the song was masked as an old horse, and at the end of evry verse the jaws were snapped in chorus".

From 'Songs Of Northern England', by John Stokoe c.1893