Police officers with an uncanny ability to remember hundreds of offenders' faces will be used for the first time at this year's Notting Hill Carnival.
Known as "super recognisers", they can recall the faces, names, birth dates and other details of offenders years after seeing them either in person or on file.
This weekend, 17 of the officers will be checking live Carnival footage in a central CCTV control room, looking for anyone whose bail conditions prohibit them from being at the event, and identifying opportunists who commit the crime.
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A man reportedly armed with several knives has been arrested in Whitehall on suspicion of planning a terror attack, police have said.
Metropolitan Police officer, Tom Harrison, has been crawling the course since the race began on Sunday morning.
The Old Bailey heard how Syed tried to get weapons online, including a bomb vest, and trawled the web to find a busy area launch an attack.