Can anyone explain why films are often released weeks, sometimes months later in the UK? I can understand that dubbing into other languages takes time, but that obviously isn't the reason.
Promotional schedules mean that the stars and director have to do 'the rounds' and in the USA that can be a big, time consuming job. Once the initial round of promotion is done (usually in the States) they can move on to other territories - hence the staggered release worldwide.
They also wait for the movie to have run its course in the US before bringing it out over so that they can just send over the reels of (well used) film for us to watch at the cinema. Anything to save money it seems !
Apart from the reasons above, there are also seasonal differences in cinema-going between the 2 countries, and films are held back to take advantage of what might be a better "slot" in the UK.