Prog in the UK immediately before it reached its heyday (say 69 to 73) was reliant on UK college and university student audiences, but once certain bands went mega, then most of those venues just couldn't afford the bands.
I caught Yes at Kingston Poly, 2 weeks afterthe Yes Album was released, and was packed in tight - but by a shear fluke managed to have a few words with the band after the show. However, about two weeks before I had seen an Island Records package tour which included Quintessence and there was tons of room to roam. I saw Krimson on their first UK tour at the Tolworth Toby Jug - if fact 'saw' is the wrong word - I only heard them because of the large size of the audience and lowness of the stage. At the same venue, I and possible no more than 10 others saw a great gig by Edgar Broughton Band. During 1971 (or maybe 72) I saw Magna Carta and Pink Fairies at Royal Holloway College's Mid Summer Ball at Egham, along with the perennials Brett Marvin & The Thunderbolts - and there was no more than 50 at each show. By the time I went up to uni in late 1972, Floyd, Queen, Genesis, Yes had priced themselves out of our union's price bracket (and please note my student union saw the last ever Bonzo Dog Do Dah gig - alas, only a little before I arrived!). I got myself on ENTS and while Wednesday night manager (normal making profits from the disco) put my one and only band on - Be Bop Deluxe, just before they turned fully pro and Peel discovered them (they were good even then)! Indeed I got blarsey (sp) since I got in free, but very selective of my choice of gigs; so memorable in some way or other Isotope (stiffer than they sounded on record), Elton Dean's Just Us, Babe Ruth (who was their support?), Focus (one of the few I left before the end - dire, very long drum solo), Kevin Ayers, Roy Harper, John Martyn, Elkie Brooks & Robert Palmer fronting Vinegar Joe, Beck Boggart & Appice (support Flash) and Sweet (doing their only university gig ever, and the only gig where the audience was limited to 18+ - but as we discovered, even free of screaming weenie boopers, they were good musicians), etc.. Got pissed with Nazareth and Robin Trower, because their roadies were cowboys and refused to bend to any fire regulars, - so having put up the equipment and then been told to move the mixing desk, they stripped the lot out and left (without informing the bands). So having given a huge amount of money back to the punters, the bands got us ENTS members happily pissed.