This is all getting rather off the topic of Great Harwood, and is rather general, so should really be in another thread.
Signalmen or Shunters need to come to a clear understanding with drivers as to what is required, because accidents happen when drivers think they are going into a long empty siding but are perhaps routed into a full one to pick up a couple of wagons. So train crews and signalmen talked as necessary to get the job done, and the signalmen would pass messages along the line by phone. There were also whistle codes listed in Sectional Appendices for drivers to indicate what they needed to do. However many shunting moves would often be known as routine daily events, so there might be no need to discuss. All that was required in the absence of fixed shunting signals (as at Simonstone) was for the signalman to set the points as required and give a hand-signal (a flag). At some stations, part of the train might be left on the main line while the engine collected or dropped off wagons, at other stations the whole train would be shunted into the yard clear of running lines and the crew could be left to their own devices. This would depend on track layout and the need to keep the line clear for other services.
There were two timetables - a public one showing only passenger trains, and another private one for railway use only called the Working timetable (WTT) showing regular goods and empty passenger trains etc. In the days of general goods traffic everywhere, there was typically one train timetabled daily to each station called the "pick-up goods" stopping everywhere on the line (bell code: 3). This would shunt as required, picking up and dropping off wagons en route. Other freight trains would generally run straight through, under bell codes describing their braking power. These would all have a destination of course, for example an oil train would run to a refinery. Signalmen were expected to know from experience and from the working timetable where trains were going. The pick up goods might run straight through if there happened to be no traffic for it, provided it didn't get in the way of other trains.
Trains which only run when required were shown in the WTT by the letter Q. Additional (non-timetabled) trains would still be planned to avoid conflict with timetabled services and establish that there was a path available for them and these extras would be advised to the staff concerned by notices or telephone/telegraph messages.