The whole folk revival for the whole of the 20th century was purely middle class. No working class collectors to my knowledge. The 60's revival was powered purely by the "educated" working class who became the middle class. Every folk club was awash with students.
The working class got on, and it's only those left behind, or those nostalgic for a lost world that never was, who are unhappy about it. However, roots are roots, so I'm still working class, but educated, and therefore researchers consider me middle class because of earnings and inferred status.
It's all bo****ks really!