Les, yes if you check the link about origins it seems clear this was more an English song than an Irish one (if that is a real distinction.) There's certainly an 'up yours if my money isn't good enough' gesture and I suppose the implication of the 'confess what I've done' and 'pardon their prodigal son' implies a temperance message.

I have gone beyond being fed up with the song. The joy that greets it in non-folk circles is so overwhelming that I find I do it just for the audience. It takes quite an effort to make it fresh but hey, that's what being an entertainer is about! I wouldn't claim that it is art but if it makes people happy that's good enough for me.