British security officers search Grosvenor Square outside the U.S. Embassy in central London September 11, 2006. U.S. ambassador Richard Tuttle will lay a wreath at a memorial garden next to his embassy in Grosvenor Square at 1:46 p.m (BST), the moment when the first World Trade Center tower in New York was hit by a hijacked plane. REUTERS/Dylan Martinez (BRITAIN)