I am with Greg on this one. I never thought of Leadbelly as a bluesman in the way that Charlie Patton, Robert Johnson or Son House were. I think of him more as an American folk singer, who covered a number of styles. "Irene" is actually a waltz - about as un blues sounding as you can get. I feel rather the same way about Mississippi John Hurt, although there is also plenty of blues and ragtime in his picking along with some fine slide playing. I think we have a tendency to lump any black folk singer of those times along with "other" bluesmen. I don't think they saw themselves that way at all.