The left , both in Britain and the U.S., put folk song into the public gaze

Yes, Jim and maybe vice versa. The earliest things in the media that stick in my mind as being either 'left' (from the workers perspective at least) or folk were that TV series (from the BBC in Manchester?), that were some sort of spin off from the Radio Ballads I think. About 1960.

Introduced by Brian Redhead - the first regional accent I recall on TV. Three firsts in one programme.