The Metropolitan Police Service is testing the technology around Soho on Monday and Tuesday.Read more
South Wales Police has used automated facial recognition (AFR) technology at several events in Cardiff since the Champions League final in June 2017.
The study found the accuracy of AFR has improved since its introduction, but does worsen in bad light or big crowds.
The Metropolitan Police used facial recognition at London's Notting Hill carnival in 2016 and 2017 and at a Remembrance Sunday event.
Its system incorrectly flagged 102 people as potential suspects and led to no arrests.