I think you will find I am anything but an advocate of PRS, I believe traditional music should be left out of anything to do with copyright and royalty payments. I have been in dispute with PRS for over 12 months and am not about to give in to their bullying ways.
The purpose of completing a set list and indicating to pRS that the material performed is nothing to do with them is indeed very important in preventing them claiming money which they are not due to, and then that money disappearing in to what they lovingly call the general fund never to be seen again particularly by folk performers.
It may be time for the government to consider regulating this industry concerning royalty payments, this would certainly prevent the practices currently employed in demanding money with threats from PRS.