Seems that even though recording a film in a cinema in the UK is not illegal, the cinema staff followed proper protocol in calling the rozzers out to apprehend the dangerous criminals.
A group of 12-year-old girls had the police called on them after they decided to bring their iPhones and iPads to a showing of The Hunger Games at a local cinema. The police officers who rushed to the scene were unable to find any recorded footage, but by then the children were too distressed to watch the rest of the film.