Just bought a ticket to see Christy in Edinburgh in June: will report back thereafter! Last time I saw him must be going on ten years ago: then a heckler shouted, "Christy, what about the potato famine?", to which he replied, "Well, what about it?" which silenced the heckler.
RE Ralph McTell: he's not the only one to have had his songs changed by a certain other Irish group, who changed words and added a 4/4 rhythm to Tom Paxton's "Every time" which was previously in pretty free time, and they also changed the title and one note (resulting in a horrible clash on the word "down" when both versions get sung together) of Eric Bogle's "No Man's Land". While folk are encouraged to "make this song your own", I do have reservations about such radical changes, and say you can't beat the author's original version.