Other than his age it wasn't vastly different from the scene described by Jack Kerouac in "On The Road" (written in 1951): '... one night we suddenly went mad together again; we went to see Slim Gaillard in a little Frisco nightclub. Slim Gaillard is a tall, thin Negro with big sad eyes who's always saying 'Right-orooni' and 'How 'bout a little bourbon-arooni.' In Frisco great eager crowds of young semi-intellectuals sat at his feet and listened to him on the piano, guitar and bongo drums. When he gets warmed up he takes off his undershirt and really goes. He does and says anything that comes into his head. He'll sing 'Cement Mixer, Put-ti Put-ti' and suddenly slow down the beat and brood over his bongos with fingertips barely tapping the skin as everybody leans forward breathlessly to hear; you think he'll do this for a minute or so, but he goes right on, for as long as an hour, making an imperceptible little noise with the tips of his fingernails, smaller and smaller all the time till you can't hear it any more and sounds of traffic come in the open door. Then he slowly gets up and takes the mike and says, very slowly, 'Great-orooni ... fine-ovauti ... hello-orooni ... bourbon-orooni ... all-orooni ... how are the boys in the front row making out with their girls-orooni ... orooni ... vauti ... oroonirooni ..." He keeps this up for fifteen minutes, his voice getting softer and softer till you can't hear. His great sad eyes scan the audience. Dean stands in the back, saying, 'God! Yes!' -- and clasping his hands in prayer and sweating. 'Sal, Slim knows time, he knows time.'
Slim sits down at the piano and hits two notes, two C's, then two more, then one, then two, and suddenly the big burly bass-player wakes up from a reverie and realizes Slim is playing 'C-Jam Blues' and he slugs in his big forefinger on the string and the big booming beat begins and everybody starts rocking and Slim looks just as sad as ever, and they blow jazz for half an hour, and then Slim goes mad and grabs the bongos and plays tremendous rapid Cubana beats and yells crazy things in Spanish, in Arabic, in Peruvian dialect, in Egyptian, in every language he knows, and he knows innumerable languages'.
Well in Clapham I don't recall bongos or people sitting on the floor, but I guess I was a 'young semi intellectual'! That was my only direct encounter with someone from the beat generation, other than once hearing Brion Gysin give a talk in Bedford library of all places (standing in for William Burroughs who didn't show- this was mid-80s).