Hilarious ! I had an incident with some similarities to this but it was at the much later 'Harold Moore's' version of Mole on a Saturday afternoon not too long before it shut up shop (I was 'fiddling at waist height' in the Collector Vinyl racks ). A bunch of loud and 'liquid refreshed' vintage Soho-type characters came in to the store, pretty well took over the place and provided a commentary on life, the Universe and everything. Very entertaining it was - and knowledgable. A year or so later what looked like the guy who was the main font of knowledge popped up on a BBC4 documentary about old jazz clubs and the debauchery that went on in them. From the BBC film, I think this guy turned out to be the head bouncer for one of those places ('The Flamingo'?)
Incidentally, as an aside - that photo I refer to shows an 'Art Ensemble' poster attached to one of the racks. I wonder if it is one of Chuck's?