I am interested, which is why I asked.
I don't think it's correct that people can't take drinks to events, it is the rules though, you can choose to sneak a beer into cineworld if you wish but you shouldn't be able to sneak objects into say the MEN or other events where there are thousands of people present.
As another poster mentioned the security from my experience don't take sweets or small snacks away from kids. Maybe this differs where in the ground you sit. The queues are annoying but surely they are for security reasons and not to take away my bottle of water?
It does piss me off though that the catering staff won't let me keep the lid on a bottle of water. I don't think the original posters issue was with his flask but because his bag was too big and he chose to bring the issue up with City and then chose to give up his season card. There are bag storage options available, not sure why he wasn't informed of these by supporter services