>...but it doesn't really matter I suppose what the original is if the oral tradition has taken over <

It most certainly does, Emma, (although it doesn't to some people) or we wouldn't be spending time discussing it here!

I have checked out several other sites just now, and they all say shuttering jams. I'd be delighted to see an authenticated set of the original words.

BTW, Wikipedia says According to remaining members of Behan's family ... the song was written with The Dubliners in mind.