The tune is one of the most primitive forms in Europe, three tones within the compass of a third. The scale in Soul Song is a trichord of la-si-do with a small hitch to re which might be an abberation of a singer. Bert Lloyd says the tune commonly sung to it is from Cheshire, UK. The tune format is very old but that doesn't necessarily make this tune the same. It certainly fits with All Souls night (pre-Christian to All hallows)