Generally, our policy was that if there were no seats sold for a showing a little while into the feature (trailers being 20 mins and starting at the advertised time) we would radio the projection department and they would just switch off the projecting equipment to save on wear and tear and power but keep the film running. They are very specific about numbers of showings though. I know the wrangling my cinema went through to try and get extra Mamma Mia showings by cancelling other films - I think in one case they pretended another print had got wrecked or something! (and zounds, they're still showing Mamma Mia now!)
Have just had a look on ze website, and it looks like they're only doing it, at least now, in the bigger multiplexes. Makes sense, as I can't imagine how they would cope with it taking up one screen most of the time at the 7-screener I just left.
When I went to Sweeney Todd, it was completely packed! Annoyingly, there were a lot of people who were still coming in when the movie had started (there weren't queues or anything outside, I got talking to a former colleague at the ice cream stand for about 20 mins it was so quiet!) so it was hard to concentrate on the film in that situation. And some eejit who came in literally 20 mins into the film just walked up and sat on my handbag! Grrr... Much preferred seeing Hairspray: myself, two mad friends of mine, two granny types and four laddish blokes in rugby gear who I think must have got lost
