Thanks for the info & links.

So far I've come up with

Paul Giovanni (II) who was credited as the composer of te Music & songs.

The following who were credited as 'Musicians'

Peter Brewis
Michael Coles
Ian Cutler
Bernard Murray
Andrew Tompkins

I gather from a linked post that Ian Cutler was the fiddler. So which of the others was which? I originally wondered were the actors credited as musicians actually playing. It looks as if they were.

There's an Ian Campbell listed in the cast. Is he a famous folkie of the period or do they just share a name?

The music seemed quite interesting, but none of the names mean anything to me.