Think you are right......... I was there for the 'This England' filming, but also remember a nite around a year or so later where the lights stayed on for the first hour-ish.......no idea why though?...
From memory live acts around then were...
Edwin (of course), Martha Reeves, Jnr Walker, The Showstoppers, Ann Peebles and IIRC Tommy Hunt, unless it had something to do with the above?..
Also I seem to recall 'Sad-Cafe' playing live prior to a Niter starting, and thier 'Gig' over-running, but again if this was the reason for the above I don't remember.