Thank you@ys123 though I'm not sure that established a general rule even then.
Thanks, hoping not as it looks like a horrible journey
My opinion would be that if you split (other than possibly the cases where the train need not call, as who knows which way it goes if it doesn't stop there) you must still travel via your split point regardless of what happens, unless it's an unplanned diversion when you were already on the train and so effectively had the choice taken out of your hands. You save money, you take the consequences of doing so.
I think that the appropriate answer depends entirely on the timetable in force at the time of booking. Especially in the context of a journey with split tickets, the timetable is an inextricable part of the contract (as it defines the rights you have, namely to travel on any Routing Guide and NRCoT Condition 14 compliant itinerary).
So if this work was, as I would have thought, foreseen and in the timetable ever since the timetable was created for the time in question, then I agree that you cannot, by default, take a route where you don't call at your split point.
If on the other hand the timetable is changed post-booking (as may happen in the case of a strike for example), then in my view this is in effect a unilateral variation of the contract - a breach of contract if you like.
Therefore, if the new timetable makes it difficult or impossible to complete the journey in compliance with the Routeing Guide and NRCoT Condition 14, then in my view the railway has no grounds to penalise the passenger in any way for
their own breach of contract.
The passenger may take any reasonable route given the nature and extent of the timetable variation; if the timetable is only minimally altered (e.g. timings altered by a few minutes) then of course this doesn't mean you can take any old route. But if half the services are removed then I think anything that is reasonable in the circumstances with a through ticket is acceptable.
In my view the same applies to unplanned diversions, or if a train's route/calling points are modified post-purchase. Again, that is a material variation of the contract so the railway cannot penalise the passenger, or deny them already given rights, because of this.
