I just noticed an interesting "feature" on the East Coast journey planner. Try searching for an open return from Ely to Kings Cross with a Network Gold Card on a Sunday evening in the near future (17 June, 1 July or 8 July, but curiously not 24 June). Apparently you can buy a Super Off Peak Travelcard (with railcard discount) for the last journey, which involves an overnight wait in Cambridge, then the 04:48 train from Cambridge to Tottenham Hale and the Underground to Kings Cross. If true, this is a very cost-effective way for people in Cambridge to reach London on a Monday morning - it lets you use an off-peak ticket during the morning peak, with a Gold Card discount before 10am, and even lets you use the tube with yesterday's off-peak travelcard! But surely it is a bug - it doesn't work with Off Peak Travelcards (only Super Off Peak), nor any sort of Single or Return to London Terminals. I can't verify it on the National Rail website, as there aren't any valid times for the return leg of the journey (the "feature" only seems to work with the outward half of a southbound return on the last train on a Sunday night).
So, assuming that this is a mistake, my question is: what rights/obligations do I have if I try to use this ticket? Are all train companies (and the Underground) obliged to honour the fares quoted by all other train companies' journey planners, even in error? (NB it's not an East Coast journey, and the Greater Anglia website won't sell travelcards without a valid return time). Would I have to actually buy the ticket from East Coast after selecting that ticket, or would I be entitled to use the ticket (purchased elsewhere) if I carry a printout from the journey planner?
So, assuming that this is a mistake, my question is: what rights/obligations do I have if I try to use this ticket? Are all train companies (and the Underground) obliged to honour the fares quoted by all other train companies' journey planners, even in error? (NB it's not an East Coast journey, and the Greater Anglia website won't sell travelcards without a valid return time). Would I have to actually buy the ticket from East Coast after selecting that ticket, or would I be entitled to use the ticket (purchased elsewhere) if I carry a printout from the journey planner?