A bit of research brings up my exact journey on Trainsplit, albeit a week after I did the trip. But the journey is not even offered when using the TPE ticket buying website, which shows 'No results found'. Are there different ticket web portals which have different rules?
The same underlying timetable, fares and Routeing Guide data feeds are used by all retailers. However:
- There are a number of accredited journey planners across the industry; these each search for possible journeys and determine valid and available fares.
- There are also a number of accredited Ticket Issuing System (TIS) providers; these each take the results of the journey planner and handle the sale and issuance of any ticket, and the associated financial transactions and accounting.
- Finally there are a number of User Interface (UI) providers; these design the website or app you interact with.
Any combination of different providers for these three services can result in a different outcome in terms of the journeys that do and don't get returned, and the fares that are offered.
It's not that one website is right and another is wrong - you're always entitled to follow the itinerary you get when you buy your ticket, or from National Rail Enquiries afterwards. Any issues with that itinerary are for the industry to pick up with the retailer through established mechanisms.
But some TISes or UIs filter out certain results if they're deemed too slow. Sometimes journey planners also can't find them in the first place, depending on how their search algorithm works and any configuration set up for the retailer.
I would say that FastJP, the journey planner behind the forum site/TrainSplit, is one of the best journey planners on the market and can often find itineraries that others won't - particularly when it comes to journeys where you are entering a less typical via point. Hence why I'm not entirely surprised that you can get an itinerary there, but not on the TPE site.