Indeed. The first person who says there's disruption and they've been told there's ticket acceptance should prompt the driver to check. If a load of people get on then there's either a massive conspiracy to defraud, or there might just be some truth in it! I know in the past around here (Hertfordshire) Uno drivers had no radio (they were expected to use their mobiles) but now they have the new Ticketer system I am sure they can be alerted very easily. I've heard of Arriva drivers refusing, despite tens of people trying to board, but Arriva has a terrible reputation locally for a number of reasons. It is frustrating when Arriva run so many buses that would be invaluable during rail disruption.