In the 1970′s the BBC’s VT department produced an annual tape of out-takes and specially recorded items by the stars of the day. It was intended exclusively for BBC staff at the time. But now, inevitably, a number of them have got out onto YouTube.
Warning: strong language!
Legs & Co. do a full musical number (1979)
Shirley Bassey, Pan’s People, Noel Edmonds/Jukebox Jury with Pan’s People
Lisa on 
Jennifer on