And it's just one personal view, DTG. It's before my time so I have no personal memories but here is an alternative view. This was posted by Dick Gaughan to uk.music.folk a few years back (as part of a post dismissing the idea that McColl invented a rule which was then rigiddly enforced in all clubs):

Anyway, the idea of MacColl or anyone else turning up at, for
example, the Hare and Hounds in Birmingham or the MSG in
Manchester and attempting to dictate anything to those who became
archetypical folk club "star" performers - like Tony Capstick,
Alex Campbell, Johnny Silvo or Noel Murphy - will bring a wry
smile to anyone who remembers the way folk clubs developed in the
late 60s/early 70s. "Anarchic" would be the wrong word as most
never developed even that level of organised policy regarding
performance content. And a Good Thing it was, too.