I haven't been to a folk club for some years now, and most early folk club organisers did jim bainbridgea great job in exposing the music (and source singers!) to a wider audience, but their decline is maybe just a natural reversion to the 'old ways' decried by the Sandman.
Participation is all- hence the rise of the 'session' as the natural successor to the pub/social/community event- these are now mainly pop-orientated with karaoke the only chance of any live singing?   
Fred Jordan's liking for a pint was well known- my dad was a lifelong Methodist, but got on very well with Fred & always got him a few bottles in when he stayed with us. I know nothing of Cox or Larner in that context, but it suited Fred and it suited me when I made a partial living in the pubs of West Cork - three pints was always part of the informal contract!
As for voice exercises, I think we live in different worlds- the world Fred and most source singers lived in would scorn such things even when promoted by some 'experts' and so would I.