This thread was started to discuss the specific situation where somebody even reasonably familiar with the network could legitimately confuse 2 trains departing at the same time to the same place by the same operator, where the only difference would be in the calling pattern.
The operating company is not meaningful to non enthusiasts. Often half the destination name is not meaningful because they don't care if is Kings Cross or Liverpool Street as long as it's London and if that is not their destination then even that may not be meaningful. So you are left with the time as part meaningful, which is a four digit number. Not really much easier to remember than a four digit train number and much more fragile because trains with similar departure times tend to depart around the same time and be on station information signs together.
If train numbers don't help, why do most major railway networks use them?
There was a severe disruption today and I was trying to change trains. I rushed to the platform and the board at Woking platform 5 showed "Portsmouth Harbour" as the destination, but the train itself showed "London Waterloo". I was going to Guildford so I knew I needed to look for the calling stops, as there are 2 possible routes. So I was confused at the train door. However the delayed train was ready to depart that the guard needed to clear the platform edge, and he needed to know if I was to board the train or not, so I asked loudly that if the train went to Haslemere, which the guard responded a firm no.
It turned out that the train was a suburban train to Basingstoke. If the platform information display showed some other destinations such as Havant, Haslemere or Guildford, I would have boarded the train immediately; and I would be doomed as the train was for Basingstoke.
In the automated announcements, a "via point" would be spoken, but it was not displayed prominently at the platform plate, neither on the 450 trains as well. This is very confusing if one misses the automated platform announcement (or is deaf), and the route is not obvious in any of the displays on the platform or the train.
And in the return journey, I was changing trains again at the same station where the two routes to Portsmouth diverge, and the train at the platform again was a Portsmouth train. Again I didn't have confidence boarding the train and stood at the door until I saw the calling stations scroll through the platform display and on the 444 on-board display (as there was severe disruption the timetable was useless to identify the trains).
If some forms of route number were used (such as 81xx for Portsmouth Harbour via Guildford and 84xx for Portsmouth Harbour via Eastleigh) I would not be confused. Otherwise, only by showing "via Guildford" or "via Eastleigh" along the destination, on the platform display, on the train (both outside and inside), everywhere where the word Portsmouth is shown, and announced repeatedly multiple times while the train is making a station call by looping "This train is for Portsmouth Harbour via Eastleigh" non-stop, I can have confidence knowing the route while I'm rushing trains when the timetable can't be followed.
Normally, the operating company can be useful because it can be used to identify the route (e.g. a CrossCountry train will not go to London), but at Woking, all trains are operated by SWR and the stocks used on both Portsmouth routes are also the same.
However, the destination is completely meaningless here, as there are 2 routes to Portsmouth, comparable to the situation where there are 3 routes to Waterloo from Guildford. And at Woking, trains via both routes can depart at both platforms - trains via Eastleigh depart at platform 4 normally but platform 5 can also be used in case of disruption, and trains via Guildford depart mostly from platform 5 but some of them are booked to use platform 4.