I can only speak from a purely U.S. perspective. I suppose one would have to outline some criteria for what constituted "revival." I was hearing folk music, or songs derived from folk traditions, as far back as I can remember - at least the mid-1940's. Burl Ives, Josh White and The Weavers, to name three more prominent acts, had a certain level of popularity, but were never considered on the same level as popular vocalists like Sinatra, Perry Como and Jo Stafford, for example. It was not until "Tom Dooley" hit the campus crowd in the late 1950's that folk music (or what passed for folk music, to some)began to emerge as a real phenomenon.

Prior to that, coffee houses were seen mostly as campus hangouts or venues for "beat" poets, chess players and assorted philosophers and hangers-on. Suddenly, they became the venues of choice for aspiring folk singers. As I remember the time, it was the first sort of popular music that invited participation and which many felt they could actually perform. That was what prompted me to become more serious about the genre.

For the more scholarly inclined, who may disapprove of acts like the Kingston Trio as "pseudo-folk" and somehow unworthy, I would point out that a lot of serious wine lovers began that pursuit by drinking Gallo, Red Mountain or Mateus rose'. If it opens doors and awakens people to greater possibility, why not acknowledge it?