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.
More top news
GMB Uber drivers are challenging the company over alleged failures to provide pay, holidays and other rights normally enjoyed by employees.
On Monday a young man from Wembley was reported missing by family who suspected he was travelling to Syria. Police were too slow, says MP.
The ArcelorMittal Orbit, designed by Anish Kapoor, is the UK tallest sculpture and will soon be the world's tallest slide.