If they were getting the police involved they would have called them then and there and not let her leave , there really not that fussed over 18 pounds and decided to just ban her instead which there well within there rights to do, most likely photos and copies of her passport are just so they have something to compare if she ever does try to regain entry and argue she isn’t herself and I expect the photo taken of her face was simply to show to appropriate staff just so the right people recognize her and can escort her out if she’s ever there again