It's a bit more complicated if the ticketing website actually accepts the booking and issues you a ticket.
The general principle is that a website/shop price label is an "invitation to treat" (i.e. they're asking you to make an offer), you make the offer and then the company decide whether to accept it or not. . . .
are we confusing Consumer Legislation with Contract Law here?
Indeed. Really a ticket is proof of a contract existing so the TOC have to offer you compensation if there's a significant change to the conditions after you make a purchase.
That is a separate issue. The question of compensation arises from a breach of contract, and the substantive terms of the contract are to convey the passenger from the agreed origin station to the agreed destination station. The Company (or Companies) will do that. The route, or even the provision of a train, is not part of the substantive terms of that contract.
A contract for travel between the origin and destination along the routes specified by the NRCoC+Routeing Guide. The route under discussion is not in the Routeing Guide. Unless using an Advance ticket that is contractually tied to the trains concerned, anyone attempting to take advantage of this bug is in a very weak position, in my opinion, and shouldn't be surprised if treated as joining the train without a valid ticket (while being offered a full refund for the incorrect ticket).
I agree.
This is clearly a mistake fare/itinerary. It is obviously a mistake to the layman. Legally, I argue no TOC has to honour it.
. . . .
Just because ticketing has happened doesn't mean the company can't cancel the contract. Clear mistake.
Yes, though the Company can, reasonably, be expected to honour the end to end contract.
. . .
a normal punter won't be versed up on routing guides etc, and the Dumbed down routing guide on the TOC and NRE websites state all routes offered are valid for travel. There is no term allowing for obvious errors.
But there is in contract law, which is why it is good advice to be appraised of the relevant legal framework.
Another piece of advice to anyone willfully seeking to exploit this error, is to travel with the neccesary cash to pay the appropriate walk up fare for the actual journey taken and to be willing to offer it up for payment at the first opportunity (whether or not the ticket is challenged, I advise the willingness to make the payment. With any luck, a ticket inspector will say 'No, that's not neccesary, I can see what you're doing here, there's been another mistake with the system' and drawing a circle in the air to represent your route, will add 'enjoy the journey').