Good guess horsey
There is a limited number of copies of each film made up and the film distributors are not keen to give out a copy unless they are sure of a good profit on it. They know that the multiplexes can show a film up to 12 times a day so always give them first refusal. Also for a film like this, they will want about 85% of the takings. That doesn't leave much for the Picture House to make a profit on with 45% being about the maximum they can afford.
There are a number of distributors but all films are distributed from London now and it takes 3 days to get here with a stopover in Glasgow before being picked up by a local courier. The film comes in small reels and has to be cut and spliced together, run through to check it etc. That takes a good half day - longer if the film is damaged in transit. This is then done in reverse for shipping the film back. Including the weeks showing, the copy of the film is out of circulation for nearly 3 weeks. Not a good situation for the distributors who want to make money.
By the way, the slowness of getting films is the most common complaint that the Picture House gets. Unfortunately, its not easy to find a solution to this. In the future films may be beamed into cinemas by satellite, which would obviously cut down distribution problems and allow simultaneous showings across the country but I suspect the equipment needed would be very expensive.
Malky