I understand your point about pop songs, Observer, but by the same token surely you would rather listen to Ewan MacColl singing dirty old town than someone do a covering it at a folk club? Personally I would rather hear a good rendition of Not Fade Away than listen to a poor performance of Lord Randall. Preferable to both would be Martin Carthy doing False Knight on the road but that would be special and he may follow it up with a BeeGees song :-) But, yes, folk clubs should be primarily songs in the folk style. Let's not go down the route of what that may be!