An elite group of police officers have the job of identifying each suspect captured on CCTV.
Known as super-recognisers, these policemen have the ability to match faces on camera to those stored in their photographic memory.
This exceptional ability has helped prosecute hundreds of people who took part in last summer's troubles.
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The family of a father-of-three from East Ham have made a fresh appeal to catch his killer 20 years after he was murdered.
The Metropolitan Police has paid £45,000 in damages in an out-of-court settlement following the 'unlawful arrest' of a black motorist.
John Cantlie, who worked for a number of Fleet Street newspapers, is thought to have been taken hostage in November 2012.