"what the artists in folk clubs do with mick jaggers music turns it back into folk music."
How - they still remain Mick Jagger's - 'the Folk', however far you care to stretch the phrase, didn't make it, didn't make it their own, din't re-make it and proliferate it in order to lake it part of their culture.
It remains Mick Jagger's property - not ours.
It is no more a folk song than is an aria from Aida sung by a Welsh Miner's choir (plenty of examples of these)
There are too many laws restricting the use of composed music to ever claim squatter's rights, and if that were not the case, the clubs have never attracted enough of the general public to even try.
many clubs have to pay P.R.S. and I.M.R.O taxes to sing public domain folk songs just in case they sing copyrighted songs during the evening.
That is just a tiny tip of the iceberg of damage done to the club scene.
"The answer was Phil Lynott. I suppose that is the folk progression."
No, it's another part of the iceberg - a folk song, made and used by working people for a century or so, being credited to someone from the establishment music factory - you couldn't have made my point better!
Jim Carroll