I would imagine that Frank knows about the hedge schools, and he certainly made no reference to ignorance.  The style of print in the broadside he refers to (which Ian C also linked to earlier on; I do wish that I'd got back here sooner so that all the references could have been in one place) in itself proves nothing, as broadside printers continued to use old type long after more upmarket printers had abandoned it.  As has already been said, the earliest attested reference we have to the song dates it to the 1830s (in England) and to the 1840s (in Ireland): it seems perfectly reasonable to place the song's origins in Ireland, but there is no point at all in getting worked up about it unless we have specific evidence.  Which, at present, we do not.

Malcolm