Question for British and European Saints fans
Zorro pretty much has the reasons spot on. Demand will far exceed supply, even more so than for pro games in the US, where you have 8 home games a year to try to get into. I'm not sure about ticket holders who didn't show, hadn't seen that figure before, but then there's not much a venue can do to control that in advance.
Good luck getting your tickets Z37, I'm registered but I would be honest and say that if a die hard Saints fan got a ticket ahead of me, I wouldn't feel too hard done by. I'll be more worried about the grief I'd get from my players on our Uni team, if the Saints lose!