There are three links to British Film Institute material on David Murnow which may be of interest. I believe films/programmes can be downloaded for viewing if one is a member of BFI. I am not fully sure of the details............Anyway, the links..........
http://ftvdb.bfi.org.uk/sift/title/769042 david munrow memorial programme
http://ftvdb.bfi.org.uk/sift/title/9453 ancestral voices programmes
http://ftvdb.bfi.org.uk/sift/series/4216 early musical instruments
I also discovered entries relating to Music in the Round but not the Munrow entry.