I think Skiffle must take come credit in kicking it off, that led to young people wanting to play acoustic guitar. Next was the move to hiring rooms in pubs instead of rather straight laced clubs in curch halls and private halls. Next was the ban the bomb movement CND, folk gave them a musical voice and bred protest singers. Ewan McColl at the same time developed the singers clubs which bred many British Folk Singers, while at the same time the big Festivals like Woodstock bred the American Folk movement. It was really a combination of many social and political factors coming together at the right time, probably the most importand and richest era of music we've ever had, I doubt it will ever be equalled, certainly never been matched