Thanks for that info Josef. I certainly hope it is TOTP as this would be in my Top 10 of performances from the show that I would most like to see recovered! Some other interesting acts on Hits a Gogo such as Steamhammer, Steve Ellis, Kiki Dee and Christie.
It was a short sequence within the show hosted by Joe Berger from what seemed to be the TOTP studio. He had quite the same task on the german tv show "Disco" some time later, which provided us with many otherwise lost TOTP performances. Alas I can't make any screenshots at the moment.