I had something similar a couple of years ago, when there was engineering works on the line between Oxford and Reading/Didcot. I got on at Moreton in Marsh (MIM) and was going to London as my final destination. No ticket office on a Sunday at Moreton so I boarded the train intending to purchase one from the train manager. He came round and asked for destinations so he could give people connections information. I told him I was going to London and was told to change at Oxford. When I asked about buying a ticket he said he had to go and unlock the doors at Hanborough and he'd come back if there was time. There obviously wasn't as I got off at Oxford with no ticket and decided having seen the Rail Replacement Bus Service as we arrived, to get the Oxford Tube instead.

I told the bloke on the gate line that I was ticketless and he told me to go to the ticket office and buy one. I stood in line and when I reached the window the bloke was baffled by my circumstances. Asked where I wanted a ticket to, I said Oxford and that I'd come from Moreton and wanted to pay. He said that I should have been sold a ticket on the train or by the "lazy" staff member at the gate but I shouldn't have been let through the barrier. As I had been let through however he said I could have the journey on FGW (as they were calling themselves at the time) and bon voyage. I said thanks and walked off to Gloucester Green to get the Oxford Tube with wifi, power sockets, a toilet etc. as opposed to the RRBS which had none of those.