Joe, some sheet music here:
http://www.hymnsandcarolsofchristmas.com/HTML/index_of_carols_uz.htm

The song is no. 33 in the Oxford Book of Carols, Dearmer, Vaughan Williams and Martin Shaw 1928 (1947) edition.
A note here: "......is here printed for the sake of the traditional tune proper to the words. It is, of course, now usually sung to 'Winchester Old' from Este's Psalter of 1592. The words first appeared in the Supplement to the New version, the metrical version of the Psalms called 'Tate and Brady', by our forefathers, which appeared in 1696....."

From this, I presume 'Winchester Old' is the tune now usually sung, and that the music with No. 33 is the 'traditional tune..'

Dunno if this will help, but in carol sings recently, I hear tunes that are sometimes different from those I learned as a child.