I have seen little in the way of the revivalist singers from the 1950s 60s and 70s ~ the likes of Ewan, Bert and the early folk club artists mentioned above ~ maybe the powers that be thought they would all go away shortly, of course the Communists were not flavour of the month in US with Pete Seeger, the Almanacs, the Weavers ~ Woody Guthrie and CND etc which may not have helped the recording of British singers ~more tendency to look towards the singer songwriters of the era
The song history seems to be all around the "revival" perhaps lost for ever or not recorded ~ which is a pity ~ I know that audio recordings were made in folk clubs but what about early visual recordings that could be collated and shown and committed to the folk song historical archive

Ray