Some years ago now, I went to a Lonnie Donegan concert in Edinburgh and couldn't help singing along. The guy behind grabbed me and just about pulled me off my chair... "I haven't paid to hear you sing, pal!"
:-(

Talking of Eliza, I would feel very sorry for her in such a situation.

I also felt for her at a concert during Kelso Folk Festival last year when she was performing with Martin.
Naturally, Martin was taking more of a back seat. Who can blame him? He's eighty, after all.
However, some ignorant heckler shouted at Eliza. "I've come to listen to Martin. Not you.."

Thankfully, he was asked to leave or did so of his own accord. I can't remember.

Anyway, it was a great concert and Eliza was brilliant as was Martin...of course.