In case anyone is interested, what appears to have happened on the West Highland, according to Realtime Trains, is as follows:
Northbound
12.12 Fort William-Mallaig ran throughout and arrived 9 min late.
09.56 Glasgow-Oban ran throughout and arrived 23 min late.
12.20 Glasgow-Oban/Mallaig ran throughout; Oban portion arrived 45 min late and Mallaig portion 54 min late.
18.21 Glasgow-Oban/Mallaig cancelled.
Southbound
10.06 Mallaig/12.11 Oban-Glasgow ran throughout and arrived 65 min. late.
16.11 Oban-Glasgow terminated at Tyndrum Lower ‘due to severe flooding’, 24 min. late.
(17.04 Oban-Glasgow cancelled, but that’s not in the timetable at
https://timetables.fabdigital.uk/nrt/dec2023/218 UPDATE 18.12 Edinburgh and Glasgow to Crianlarich, Oban, Fort William and Mallaig.pdf, and it says it wasn’t activated until 19.36; does anyone know what that’s about? I doubt if it was intended to run).
16.01 Mallaig/18.11 Oban-Glasgow: Mallaig portion terminated 37 min. late at Fort William, and Oban portion cancelled.
19.00 Fort William -Edinburgh/London cancelled ‘due to planned engineering works’.
18.15 Mallaig-Fort William cancelled.
I presume the Tyndrum termination was unplanned; I wonder what arrangements were made for the passengers or what the units did next.
(Presumably they returned to Oban at some point, which I'd guess might have been the best option for some passengers too).
When I first looked late yesterday, the 12.20 and the 16.11 appeared to have vanished after Glenfinnan and departure from Oban respectively, even though it was well past the time at which they now seem to have reached Mallaig/Tyndrum; presumably the further times must have been added later.