Liverpool Lime Street - Manchester Oxford Road.
The only stations with barriers are Liverpool South Parkway, Warrington Central and Man Oxford Road.
Lime Street only has barriers on platforms 1 - 5, but all (or nearly all) Northern services to Manchester Oxford Road now use platforms 6 - 10, so if you are going to any of the intermediary stations not inc South Parkway and Warrington Central you are laughing!
9 times out of 10 the conductor doesn't bother coming through the train, and if they do you can just buy a ticket. If it's a Pacer joined up to a Sprinter, or two Pacers joined up, there's no incentive at all for the conductor to check tickets.
And if its a rush hour train with 2 carriage that is standing room only (not uncommon with Northern) or the last train of the evening on a Friday night where everyone is packed in like sardines the conductor doesn't bother going through the train. Last train on a Saturday used to be the same, but with the strikes, well...