Pseud,

Robin Hall & Jimmie MacGregor did appear on White Heather Club. But prior to this they had a much larger exposure from their long run on the BBC Tonight" TV programme.

"At least some of the political aspect may have come from the states (via Blues, Lomax etc)."

Believe it or not the UK did not need Lomax to teach us about politics and your suggestion that the blues had any political influence would suggest that you know even less about that scene.