Opening up The Dead's Workingman's Dead, certainty over the real identity of Uncle John probably died along with Jerry Garcia. Bluesman, Mississippi John Hurt is one theory; friend of the band, John Cohen is another. John The Baptist or the Grateful Dead's former manager Jon McIntire have been mooted. Then, of course, it could have been completely autobiographical with Uncle John just being a substitute for Uncle Jerry. Either way, it sounds like listening to him and his band play down by the riverside in late 60's San Francisco would have been a great experience.