According to Sci-Fi Wire, this change is not due to the similarities between the movie and the recent bombings in London. It is moreso due to time needed for post-production.
In this movie, a young woman is led by a masked revolutionary man, and must fight for her freedom in a futuristic and totalitarian society in England.
The movie was produced by the Wachowski and Joel Silver brothers, and stars Natalie Portman and Hugo Weaving.