The officials, who spoke on condition of anonymity, would not elaborate about the nature of the evidence, but they said they were following up on it to see where the information took them. In late March 2004, just weeks after the deadly Madrid train bombings, British authorities launched Operation Crevis, which resulted in the arrest of eight British Muslims, ages 17 to 32, on suspicion they were planning or instigating "acts of terrorism." At the time, police sources said the suspects were linked to "possible Islamist terror."In the raids, more than 700 British police fanned out at sites in London...