Manchester Arena attack: Aerials of security in London

Manchester Arena attack: Aerials of security in London; ENGLAND: London: EXT AIR VIEWS (AERIALS) Victoria Memorial at Buckingham Palace / tourists outside gates to palace / police officers on The Mall / police at gates / guards in palace grounds / Grosvenor Square and US Embassy building / flag at half mast over Embassy building with bronze eagle sculpture / police officers on street / security vehicle parked / police and security officers at gate with vehicle ramp / Hyde Park and Marble Arch / police vehicles under Marble Arch / traffic along around Marble Arch / Oxford Street / London cityscape / Ludgate Hill and St Paul's Cathedral / security barrier fences around cathedral grounds / police vehicle and officers