I was musing and remembered something of relevance. Back in 1970 my mate Mike and I got tickets for a live recording of a radio show at the Apollo in Ardwick, Manchester. All I can recall is that it was hosted by Wally Whyton so I looked him up and it seems his show was "Country meets Folk". It ran from 1967 to the mid 70s so it certainly seems that there was a mass market for this crossover. If I can find any more details, I shall post them :-)