Dick Snell was in The Critics Group when I joined in 1969, though I lost touch with him some time in the mid-70s.
He always used to introduce the song with the explanation that a ranter was one of the itinerant hellfire and brimstone clergyman that travelled the English countryside in the 18th century generally making a nuisance of themselves.
Don't have any further information on this but would welcome enlightenment.
Jim Carroll