Although the NRCoC entitles you, in certain circumstances, to use two or more tickets for one journey without the train having to stop at any intermediate station, the train must still pass through those station/s, as it must cover the entire journey. (I do not take "cover the entire journey" to mean that the combination of tickets must only cover the entire journey of a "normal" timetabled service - how would this work for journeys where two or more routes exist?). As far as I am aware, there is no automatic right for ticket combinations that are "normally" valid on a service to be valid when that service is taking a diversionary route, unless the diversion happens because of unforeseen disruption (e.g. line blocked south of Stafford because of a signal failure, so Virgin Trains to/from London that normally travel via the Trent Valley are diverted via the West Midlands).
Point-to-point "Any Permitted" tickets must remain valid even when a train takes a diversionary route that is not a permitted route. This is because "Any Permitted" tickets allow you to travel on any timetabled train on any permitted route. When a timetabled train is not available and is substituted by a train which takes a diversionary route that is not a permitted route, the "Any Permitted" ticket must continue to remain valid so as not to contravene fares regulation.
--- old post above --- --- new post below ---
When trains are diverted, tickets that are valid by the diversionary route become valid (e.g. Rte: via Hebden Bridge becomes valid on TPE services, if they go via Hebden Bridge), however tickets that would have originally been valid, remain valid, as I understand it.
There is no way for a "regular" customer to know that their train is diverted simply by looking at a standard timetable. It is only by looking at sites such as Opentraintimes.org that they can determine the passing points of the service.
I disagree. If a customer wishes to use an unusual combination of tickets, it is their responsibility to check that such a combination is valid prior to travelling. Otherwise, that customer must buy the normal point-to-point fare, which will always be valid on a point-to-point service (as explained above).
To claim that "ticket combinations that are normally valid must continue to remain valid when a train is diverted as the customer may not have known that the diversion was in place" is illogical. If the customer is not aware of the route their train is taking, how are they aware that their specific ticket combination is valid?
People may disagree with me on this, but I am of the opinion that split-ticketing is an option and if you decide to use it you accept the associated risks, which includes the fact that your combination of tickets may not be valid on certain trains on certain days even when valid normally.
