The timeclock for this episode lists a recording date of 29th June 1979. For the first time a projected transmission date is also listed, with a date of 24th October 1979. (The episode eventually aired the week before).
This indicates that somewhere between this point and the recording of the previous episode, two weeks earlier, that the BBC had confirmed the broadcast schedule for the programme.
This indicates that somewhere between this point and the recording of the previous episode, two weeks earlier, that the BBC had confirmed the broadcast schedule for the programme.