I might be over-exaggerating here (in regards to the Joe Harriott anyway). I bought just over 100 cassette tapes at a car boot last week. The previous owner was a serious taper that recorded a load of live gigs in London during the 70's - 90's. He also recorded tons of jazz radio shows which are mixed in there. I have listened to a handful so far (highlights being Art Pepper, Dexter Gordon, Art Blakey at Ronnie Scotts) but I did see a couple of Joe Harriott's in there (and a Tubby Hayes tribute). Not sure if its a radio show or live recording though (the radio shows always seem to be live recordings though, so still interesting).