The earliest version I am aware of (and that doesn't mean its the earliest version) comes from the Robert Johnson era. It is absolutely a blues song, but references to what constitutes blues are as varied as what constitutes folk. The Blues are not monolithic. If someone is trying to tell me this derives from an English song, they will have to give me some cites. I don't have any problem with the fact that it would come from England, but I am very dubious that this one did. This could be a very interesting thread.

All the best,

Mick