'Original' Erin Go Brách?

At 2.52 on 24 June I wrote:

According to Dick Gaughan, the Scots text is C19. So did Peadar Kearney base his song on this? His nephew was not, after all, averse to 'adapting' trad stuff in the time-honoured fashion

Shortly after which, surprise, surprise, someone raised Dominic Behan's The Patriot Game using the trad tune The Nightingale (which didn't, of course, deter Dom from having a go at Dylan for doing the same with With God On Our Side).

So what were Kearney's sources?