I've recently wangled a couple of lunch breaks and managed to create a time/distance graph for my North Cornwall line timetable. It's not complete as I still need to confirm workings to/from Mawgan Porth but it has thrown up a couple of anomalies.
The first anomaly was the Up 11:30 goods train passing the ACE between Launceston and Tower Hill. This must have been a problem created by using timetables from different periods. I've altered the timing of the goods slightly by shortening its stay at Launceston so that it reaches Tower Hill just before the ACE. Not sure if this is correct so if anyone has a 1961 goods timetable for the line please let me know.
The second anomaly was with the Down 7:15 Halwill departure which, when compared to other down trains, seemed to take too long to travel between Tower Hill and Launceston. I've double checked the 1961 timetable and the times are correct. My only assumption is that the timetable does not show the arrival time at Launceston it only shows the departure time. So I've altered this to have a 13 minute stop at Launceston, to drop off newspapers and parcels.
Neither of the anomalies have affected what I'm trying to do at Grogley Junction and the surrounding area but I like to try to get things as correct as possible with what information I can find (please note I did say 'try').
The thought of creating a time/distance graph had not occurred to me until Micky suggested it in a recent comment. Creating one has shown how valuable these graphs are to confirm timings for timetables. From now on I'll be trying to use one or more time/distance graphs while creating a timetable for the local workings around Grogley Junction.