TOTP November 23rd 1978: Legs & Co. dancing to Sylvester’s Dance (Disco Heat).
From the old blog, Friday, 18 July 2014:
Around a minute-and-a-half in, the lighting engineers seems to have woken up in panic “What? Sylvester? I’m supposed to dim the lights right down for a special effect here, aren’t I?” and the lights start fading. Cue shouts from the gallery. “You idiot! That was the last one!” laughs the sound engineer at the next desk. Soon everything is restored.