Llanigraham
On Moderation
With the exceptions noted upthread (DSB holders etc) on-board ticket sales have to completely stop. Even if that results in lost revenue, that is the ONLY way the message will get across - if you get on and travel anyway, you WILL get a PF. Not might, will.
Not possible!
If there are only card machines available at a station then you have to allow cash buyers the option on the train.