Jennyann, you've got me thinking. I believe you're right that only the 5s and 7s stopped in Victoria Square opposite the Council House, while the other buses that went up Broad Street (1, 3A, 6 and 9) stopped in Paradise Street.
The 'Stage' plates were put at the fare zone boundaries, but outside the city centre, a 'To City' or 'From City' plate would be put over every bus and tram stop sign. which it was claimed made it unnecessary for the destination indicators to be changed at termini. Only the outer terminus was normally shown.
Peter