I understand the purpose of the electric staff as it was used back in the day, but I can’t get my head around why the electric part is necessary.
For example, a Grange train arrives at Albert Park and receives the staff for the journey to Grange. Now if another train arrives at Albert Park, it cannot (or is impermissible) to continue to Grange as the staff is with the train already on the Grange line. It will have to wait for the train to return so the staff can get passed on to the other train.
It seems simple to me, so why is it necessary to have the electric staff machine, or more than the one staff for that matter?
Lastly, if I remember correctly, the Grange station became unattended – or at least unattended most of the time - while the old signalling system was still in place. Likewise the Albert Park station. So what system of safe-working was in operation in that period?