Thanks Reliefman, I didn't know he-who-thinks-he's-god had ordered it.
However, there are ways to politlely ask customers to move to another part of the pub, and the girl who told us doesn't know that.
Again, if no-one is eating or waiting to eat, why can't customers use the room? Makes no sense to me, since the pub is usually busy and there is nowhere else to sit. Being York, there is a tendancy for hen parties to take over the other room, making it a place to avoid for someone like me and my mate who just want to have a quiet beer or three together.
The alternative is to go somewhere else, but why should we?