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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Rebecca Casserly was on her way to buy a coffee in north London when her phone was suddenly snatch from her hand by a man riding a bike.
Lee Curley took more than 120 pictures and videos of his attacks on the girl, said to be under the age of 13.
Council workers uncovered the AK-74 concealed in the undergrowth.