Hugh Roberton conducted (and probably/possibly started?)The Orpheus Choir, based in Glasgow. Their singing is gorgeous (tho not 'folk'!), very distinctive - timeless - and they were very well known in the - '40s, '50s? They sang 'Scots Songs', also psalms and hymns and did the annual Messiah concert in the St Andrews Halls in Glasgow (behind the Mitchell Library as I recall?
After the Orpheus disbanded . Hugh Roberton died (sorry I do not have facts, just vague memories from childhood) The Phoenix Choir arose from the ashes -- not sure who organised this? but our music teacher at Hamilton Academy Pete Mooney was the conductor in '60s - and allegedly used the Hamilton Academy Choir as a source of new Phoenix members?! (well, that's what we all thought as teenagers!)
I am sure there are others who can fill in gaps / correct my waffling.