On an Avanti train a few weeks ago, there was a passenger with learning difficulties who had clearly been given a ticket and told to show it to the ticket inspector when they asked for it. The passenger held a day return Carlisle to Preston, route via Penrith. It wasn't a split ticket. The train manager told the passenger that her ticket wasn't valid because the train wasn't scheduled to stop at Penrith, and insisted that she buy another one. The passenger was very confused and distressed, but the train manager simply insisted that she take out a debit card and sold her a new ticket.
I'm pretty certain that a ticket routed via Penrith is valid whether or not the train makes a stop there, but wasn't absolutely certain so didn't say anything at the time. Later in the journey, I went and found the train manager and quietly, out of others' hearing, suggested that she might have made a mistake with that lady's ticket. She told me she hadn't, and walked away. A little later, as she walked through the train, she made a point of stopping at my seat and told me that selling tickets was her job and please not to think that I know better than she does, before walking away again.
Regardless of whether the ticket was valid or not, though, the way the vulnerable passenger was treated was appalling. As was the way in which she went out of her way to make the scene that I had tried to avoid.