[ The International Working Group on Video Surveillance (IWGVS) published an open letter to the Mayor of London Sadiq Kahn on 27th January 2017 , asking him to reverse a decision of his predecessor Boris Johnson.
This article lays out the back story to that letter.
Ultimately the best they can do is a total figure surveyed equivalent to 0.69% of the drivers affected by the policy - surely a quorum in anyone's book. In response to a Mayor's Question in 2015  he said: So to summarise, of the 0.001% of Londoners surveyed, almost 8 out of 10 people who mostly thought the police already had access to Tf L's ANPR cameras were in favour of a policy that would allow their somewhat inaccurate view of reality to become more accurate.
In 1929, further to inspiring a parliamentary committee to investigate Ministers' Powers, then Lord Chief Justice, Lord Hewart coined the phrase "Administrative Lawlessness" to describe a worrying trend in English politics - the exercise of arbitrary power, where decisions are made in the shadows, not based on evidence and without proper scrutiny.
Hewart wrote : "Arbitrary power is certain in the long run to become despotism, and there is danger, if the so-called method of administrative "law", which is essentially lawlessness, is greatly extended, of the loss of those hardly won liberties which it has taken centuries to establish." In 2017 Hewart's language may seem antiquated but in our not so distant past words like "liberty", "constitution" and "freedoms" were in common usage.
When Johnson was re-elected in May 2012 he did get a free gift, the job of Police and Crime Commissioner for London which now comes as an added extra to the mayoral job.
Johnson palmed the job off immediately (via delegation of powers) to his deputy, Stephen Greenhalgh.