You are in for a treat, Roger. So far, along with Ian's book, I would say that this book (and probably also along with the meandering 'Innovations in British Jazz' book) provides the best overview of the 1960s British modern jazz scene of any I have read. I plan on downloading that addendum this weekend to find out more about Big Pete Deuchar etc.
I remember George Chisholm being on the TV a lot in that 60s/70s period - especially on children's TV, 'Crackerjack' and the like as well as that minstrel show. Usually his act was mainly slapstick followed by a few riffs on the 'bone. That would be around the time that Kenny Wheeler & co. were doing Mr Benn.
It's a shame that there is no recorded footage of that Wally Whyton show with the musical backing. According to the book, Danny Thompson bought and paid off his London house on the proceeds !