Excerpt:
On January 15 last year Channel 4's Undercover Mosque documentary showed preachers at mosques in the West Midlands urging the killing of homosexuals and lapsed Muslims.
Two weeks later anti-terror police arrested nine men on suspicion of involvement in a plot to kidnap and behead a British soldier home on leave in Birmingham. Five were convicted later.
The raids were followed by widely reported claims from one of those released after questioning that Britain had become "a police state for Muslims" and that those arrested were suffering trial by media. The atmosphere in Birmingham at the beginning of 2007 was febrile. West Midlands Police found themselves expending as much effort defusing community tensions as investigating the kidnapping plot.
As the fear of disorder receded, however, they began an investigation into the Channel 4 programme — obtaining a court order to seize hours of footage. That inquiry quickly shifted from looking at the preachers to examining the actions of the film-makers.