I have copies of this ballad in four different books, all of which agree that it was first seen in print in 1558. However, the only one to quote the tune in question is the Oxfor Book of Carols, and then only as an alternative. It was set by RVW to the hymn 'I heard the voice of jesus say' (words H Bonar 1808-89), along with many other folk tunes he used when he edited the English Hymnal in 1906.

This can also happen in the opposite direction. I was once singing 'The Blacksmith' to its usual tune, and a lady got up and walked out, muttering darkly about the sacrilage of using a hymn tune for a folk song.

Personally I think it's a great tune and you sing which ever words appeal to you.