In 2007 Panorama made a programme in Blackburn, which was becoming segregated along ethnic and religious lines. Now Panorama has returned and found a town that is even more divided. Some parts of Blackburn are almost entirely Muslim Asian, while other parts are only lived in by white residents. This kind of social segregation has been described as a national crisis, despite decades of government policy aimed at bringing people together. So why do such divisions persist? Panorama visits one town to answer that question and illustrate the impact of social segregation on local communities.