I do remember McTell saying that, though when I heard him (Hastings Folk Fest, eons ago) he was perfectly polite about it and not at all arrogant. In fact he seemed bemused that the other version had acquired such a life of its own. He remarked that after some gig where he'd performed this song, a member of the audience came up afterwards and informed him that he was doing it wrong, and "corrected" him! Perhaps by Hastings this sort of thing had happened so often that he simply grew philosophical on the subject -

I also recall that at the Planxty Reunion gig in Hammersmith (I'm not sure whether it was Christy or one of the other band members who spoke) when they were about to play a Horo [spelling?] the audience was asked politely BEFORE the number began to please not clap, as its rhythm was very complex and it wouldn't work. Andy Irvine had just collected this piece on his travels and obviously he wanted it to come across well. Horos were unfamiliar to most Irish-music fans at that time, so this was an introduction to something new.

And did the audience refrain from clapping along? Did they HELL!!! Did it ruin the number? Well, perhaps not totally but certainly to a large degree. The rhythmic subtlety was completely obliterated, and you simply could not HEAR it with all the extraneous noise coming from the wrong side of the stage. It's already been pointed out that audience-clapping gets out of synch even in a straight reel or jig and drags it down - you can imagine what this ended up sounding like!

And afterwards I still heard mutterings of resentment that the performers had asked the audience not to "join in".