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The figure “4.2 million CCTV cameras in the UK” is often quoted, from everyone to the BBC to the House of Lords, but where does this figure come from?

The statistic comes from a paper published in 2002 by academics Michael McCahill and Clive Norris. The study was based on a survey of the number of CCTV cameras in two busy south London streets: Putney High Street and Upper Richmond Road.

The researchers sampled 211 “premises” - pubs, shops, banks and office blocks – and found that 41 per cent had CCTV systems, with an average of 4.1 cameras per system. They then assumed that this CCTV coverage was roughly the same across London, and multiplied by the number of VAT registered businesses in London. They then added the number of public camera based on transport, hospitals, schools, etc.  They then managed to produce the number of cameras for the London population, 500,000 for 7 million people. They then multiplied up to get the number of cameras in the country – 4.2 million. They have gone from two streets (two very busy streets) and extrapolated out across the entire country.

Lasers have been looked at defeating CCTV cameras with a vareity of different reports on the results. One of the main reported problems is that laser are too directional, and as such if not pointed directly at the CCTV lens do not work.

Hence people have used an arrary of IR LED lights to resolves the direction issues.

One post report the used of a laser used to defeat CCTV that was activated by a mobile phone, the idea being that laser is fastened into position prior to it being activated -  obvious that assumes that the laser and CCTV camera are both fixed and will not move.

We are repeatedly told the CCTV is here to protect us from the worst of the worlds offenders, including terrorists and international criminals. Despite the obvious flaw in the argument that suicide bombers are not bothered if they are filmed blowing themselves up (especialyl as they normally release videos to that effect shortly afterwards anway), there is the additional issue that if a person wants to hide their face from a standard CCTV camera it is incredibly easy.

A person can hide their face with a beard, material (mask/bandanna/etc), or they  can go slightly more high tech and use infrared lights.

A single point source of a IR Laser, if pointed directly at CCTV camera will flare the camera, however that involves a laser and the user to point and hold the laser directly at the camera. However, if the individual uses and array of IR LEDs then the effect is the same, as a single directed laser.

The idea is relatively simple, the user places IR LEDs in a “head torch, such as the one pictured inset. IR LEDS can be bought for just 79p and  LED head torches can be bought for just under £5 .  IR – Infrared - with a range of 750nm to 1mm has a range below the human eye, but can still be detected by CCTV cameras.

Below are the effects of using this type of  technology. There are flaw in this anti-CCTV devices. The LEDs need to be powerful enough, the and CCTV camera needs to not have an IR filter. It is is also possible, to enhance the blue green specturm after the incident to try and recover a better image.