Several things still not clear here.
OP's 23 tracks. Are they of Bert singing?

Thanks, Ross, but I'm well aware of the contributions made by all 4 people mentioned prior to the onset of the revival which they all contributed enormously to. The question in Bert's case was why would he learn such songs and who would be his audience at the time? There was little interest in song at EFDSS at this time and there were no folk clubs. I must reread the Bert and Ewan biographies.

I'm pretty sure my Bert 78 is on HMV. Has anyone got a definitive listing of Bert's 78s?