How many CCTV Cameras are there in London? (Update for 2020/21)

How many CCTV Cameras are there in London? (Update for 2020/21): Research by CCTV.co.uk concludes that in London there is now 1 CCTV Camera for every 13 people, meaning there are now 691,000 CCTV Cameras in London (2020/21)