Folks,
Aberfeldy had a dual-system where normal operation would be Train Staff but at times of more traffic a tablet could be used. See BoT Extract:
MT29/95 Aberfeldy
'Oct.15, 1946 – Mount reported that in 1938, the LMS decided that the Branch originally worked by tablet could be made to operate train staff with one engine in steam most of the year. Arrangements to introduce the train staff vice the tablet by inserting a king lever at Aberfeldy, which had fixed to it a train staff in shape of an Annett’s Key lock attached to the King Lever No.13, which normally stood pulled. This lever could then be restored to the midway position which allowed the Up and Down running signals to be replaced to normal (danger). Thereafter the King Lever could be fully replaced, removing the back locks from Nos.4 & 10, which could then be placed normal. At the same time replacement of the King Lever to normal permitted the section tablet to be withdrawn from the mechanical control instrument behind the King Lever while the train staff became locked in the King Lever lock. This control instrument was of McKenzie & Holland design, adapted to work in conjunction with the King Lever. When the tablet was locked in the control instrument, the block instruments were out of phase at Aberfeldy and Ballinluig. The main Ground Frame at Aberfeldy had 13 working levers and was controlled by an Annett’s Key. Another 2-lever Ground Frame worked the Platform run round crossover. There was a 4-lever Ground Frame at the Aberfeldy Distillery and similar 4-lever Ground Frame at Grandtully, both controlled by either train staff or tablet whichever was in use.'
I'm going to attach a couple of drawings of mine showing detail. Note the drawing earlier in thread is an M1 track & signalling NOT an M5 signal box diagram. I attach both.
Aberfeldy-M1-1934-Rev.2-rot.pdf
Aberfeldy-M5-1947-Rev.0-rot.pdf