Revenue Protection on AGA is dreadful. They pay no attention on the trains to expired tickets (I always have valid tickets, sometimes I forget to switch them but they don't notice).
I've also noticed that on intercity trains, where people can buy tickets on the trains, they've stopped checking tickets now, at least when I've been on board.
The people on the barriers at Liverpool St are rude and offer no assistance at all.
The experience of this person is in huge contrast to my experience with Virgin. Booked advance tickets to Manchester for two people. Collected tickets from the machine at Liverpool Street, several months before. For some reason, I didn't check them properly - saw 4 'tickets' and thought all ok, despite being a seasoned rail traveller. Got to Manchester fine, but on checking the tickets before we came back, I realised I had one ticket and one receipt. Bought a full price single back and emailed Virgin. I was reimbursed within 3 days.