I purchased one late last year from onboard a conductor on XC when boarding at Lydney with my Y-P discount it was a Explore South Wales, I don't think they are allowed to be sold-on board, but the guard said he could do it.
Thanks for that.
So it's possible to sell them on the train like any other rover ticket. So if you ask for one from a conductor whether it's an ATW train or any other, can they refuse to sell you one, or are they obliged to sell you the ticket you request?
Some companies such as Northern, Arriva Trains Wales and Scotrail appear to have local instructions telling guards not to sell them and giving reasons such as the boxes (where applicable) won't print or not to sell them to prevent the risk of fraud but it's perfectly possible for them to be sold from an Avantix Mobile ticket machine.
Ironically 158757 bought one from Virgin Trains at Manchester Piccadilly where the boxes printed incorrectly (following the introduction of their new TIS) and he bought a new one onboard ATW and applied for a full refund on Virgin Trains bought rover. In that instance I think he got 4 Date boxes for a 3in7, if i recall correctly .