"If the English folk clubs are really that hard-nosed about hearing only authentic singing"
This is one of the 'Great Lies' of this argument from day one of all these arguments - they aren't, nor, in my recollection, have they ever been
The clubs were first set up on the basis of drawing attention to "authentic" (if there has aver been such an animal) folk songs, but from day one, they have gone alongside newly composed songs.
The revival was based on the idea that we didn't have to be just listeners to what was churned out and sold to us, but we had a body of songs that didn't belong to any record company or individual which we were free to take from and use in whatever way we saw fit.
From day one, people were composing new songs; one of the architects of the revival, Ewan MacColl, probably became better known for his own songs than for the traditional ones he researched and introduced to the scene.
Despite this fact, if you turned up to a club performance or a concert, the songs you would hear were something like %75 traditional - modern and traditional went hand in hand.
Very few clubs had a trad only policy (I don't think I ever went to one in fifty years).
It has never been the argument that clubs should be trad only, just that traditional songs should still be their basis - that is where wer should be able to go and should be able to send others to listen to folk songs.
The folk scene used to be a place to promote and enjoy an important and greatly neglected part of our culture - now it has largely become the stamping ground of a bunch of people not imaginative enough to come up with their own name for the music they wish to perform, nor talented enough to make it on the pop scene, where their real interests lie.
In the process, they have naused up an opportunity to pass on the huge body of songs that have been passed down over the centuries and still have great relevance and entertainment value to those who are prepared to give them a chance.   
I don't think I have met with as much contempt and disinterest of folk songs and the people who were generous enough to pass them onto us as I have here from some quaters.
Maybe we should think about another category - how about 'Yob Folk'?
Jim Carroll