Two ticket sellers are utterly convinced that the Network Rail discount card is valid before 10 am on the High Speed trains. I give in and buy a Network Rail card.
Two more ticket sellers are utterly convinced that this is so. I waver and buy that 1/3 off ticket for a 6:47 am train. Which is before 10 am.
I ask a fifth ticket seller and he disagrees. He says that those first four ticket sellers were poorly trained and misled by the options on their Portable Ticket Machines. On the other hand, he refuses to sell me a top-up ticket, telling me to ask the on-board ticket inspector to make sure it's really not valid.
On the morning train: For the first time ever on a high speed train, there is no ticket inspector. There are no inspectors at Canterbury. The gates are open. I have arrived in Canterbury for a discount of more than £10 on the usual ticket price.
By now it's after 10 am, so my ticket is clearly valid. There IS a ticket inspector on my train home. He's fairly sure that, as per all text printed everywhere, the Network Rail card cannot be used before 10 am. On the other hand, he then goes to double-check this with his colleague, just in case he's wrong. His colleague agrees.
This makes a total of 4 Southeastern Rail employees who are sure it IS valid and 3 who are sure it is NOT valid. The majority still hold otherwise, but I'd err on the side of the ticket inspectors and buy the full price ticket next time.
The hilarity of it is, I know those ticket sellers will all try hard to sell me a discount ticket; I shall have to protest their attempts to save me money. Worse, they're more likely to recognize me as someone who has a discount card since they've all talked to me at length about it. On the bright side, my knowledge was obtained at a £10 discount.