United Press International: A 29-year-old woman described as an environmental activist has been arrested for throwing green custard on a top British official, police in London said Sunday. An unidentified Metropolitan Police spokesman told CNN the woman, identified as Leila Deen by the activist group Plane Stupid, had not been charged in the Friday attack on British Business Secretary Peter Mandelson. Mandelson was hit with a green substance thought to be custard when he arrived for a carbon emissions …