FactCheck: how many CCTV cameras?
Updated on 18 June 2008
How two streets in Putney spawned a nationwide statistic that runs and runs.
"A CCTV camera for every 14 citizens."
David Davis, resignation statement, 12 June 2008
The former shadow home secretary's resignation statement, delivered last week outside the House of Commons, railed against the erosions of civil liberties.
David Davis reeled off a nugget on the level of surveillance in Britain: in true big brother-style, there is now a CCTV camera for every 14 people.
It's a precise-sounding figure, and one that Davis is far from the first to quote. In the past year, it's come up in The Times, The Independent, The Telegraph, The Observer and the Daily Mail, among others.
So if it's so widely reported, it must be an established fact, right?
One camera for every 14 people comes with a partner statistic: that there are 4.2 million security cameras in the UK.
The pair of claims come from a working paper published in 2002, by academics Michael McCahill and Clive Norris. FactCheck alarm bells are already ringing. It's now 2008, so is the figure still up to date?
It's hard to say, as there are no official (or even unofficial) statistics on how many CCTV cameras there are. The information commissioner doesn't know, the government has repeatedly told parliament that figures are not collected, and any tally of publicly funded cameras wouldn't cover any small screens set up in the likes of cornershops.
We can look, however, at how the Davis-quoted figure was calculated.
The basis comes from 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" - banks, estate agents, pubs, shops and office blocks - and found that 41 per cent had CCTV systems, with an average of 4.1 cameras per system.
By assuming this is "broadly representative" of CCTV coverage across the whole of London, the authors estimate that 41 per cent, or 102,910, of the 251,000 VAT-registered businesses registered in London would have a CCTV system. Multiply this by 4.1 and there would be 421,931 cameras.
They then add the cameras operating in other public institutions - such as open-street systems, transport, hospitals, schools etc - and reckons it's "not unreasonable to 'guesstimate' that Londoners are monitored by at least 500,000 CCTV cameras".
Maybe it's not unreasonable, but it's hardly concrete proof, either.
The report then estimates that, as London has 7.2 million residents and the UK has around 60 million, the country has at least 4,285,000 cameras, approximately one for every 14 people.
Bingo - there's the claim, but we've got to it based on two London streets, multiplied out to reflect the whole of London, and then multiplied again to reflect the whole country.
If Putney High Street was more representative of the wider world, you'd expect, according to the authors' methodology, there to be more than half a million business CCTV cameras in London.
So how reliable is the figure? It's hard to say in the absence of other such studies, but a hefty part of the estimate comes from the idea that around 41 per cent of businesses have a CCTV system.
This 41 per cent is the average of the two streets used in the sample, but it masks a 15-point difference between them. On Putney High Street, 59, or 49 per cent of the institutions surveyed had CCTV; on Upper Richmond Road, it was 18 or 34 per cent.
If Putney High Street was more representative of the wider world, you'd expect, according to the authors' methodology, there to be more than half a million business CCTV cameras in London, not counting the additional public systems.
But if Upper Richmond Road was, in fact, the more representative street, the number would be more like 350,000.
Even if we accept the 41 per cent stat as gospel, it's questionable how appropriate it is to apply it to businesses en masse. According to the working paper's appendix, 57 per cent of the institutions in Putney High Street were chain stores or small shops, and 19 per cent were restaurants, pubs, bars or cafes.
But a quick analysis of VAT-registered businesses across the country in 1998 (the year that London had the 251,000 businesses quoted in the report) suggests that only around 25 per cent of them were sales, restaurants, bars or "other service activities" - and that's a generous estimate.
This doesn't necessarily prove anything about their number of CCTV cameras, but it does illustrate once again the potential pitfalls of extrapolating the results of this small sample of data to apply to all businesses in the country.
One alternative estimate of CCTV camera numbers comes from a trade association, the CCTV User Group.
Its director, Peter Fry, reckons there are around a million, and probably no more than 1.25 million, "public" cameras. But he cautions that, although based on his pretty extensive databases, this isn't "much more than a guesstimate".
When counting cameras, he reckons it's also important to look at what exactly they are monitoring. "Some may be in a private business such as a corner shop, some may be one camera outside a pub that isn't actually monitored, something like a building society may have more cameras 'back of house' which are not actually on the public," he said.
Fry's figure includes official systems such as those run by the police or local authorities, plus "quasi-public" systems such as those in hospitals, universities, shopping malls, supermarkets, airports, buses and amusement arcades. However, it wouldn't include a private camera in, say, a tiny shop.
So it doesn't necessarily contradict the 4.2 million figure, or support it - we're back to the original problem of just not having enough evidence available.
The Putney guesstimate is our current best-guess figure of the number of CCTV cameras - or the number in two London streets several years ago, at least.
This doesn't means it's right, or wrong, but it's certainly not the kind of direct evidence suggested by Davis's claim.
One glimmer of enlightenment may come from the Scottish government, which is currently trying to review how many cameras there are north of the border.
Its findings have yet to be released, but hopefully before too long we should have a more definitive answer to the camera-counting conundrum - in one part of Britain, at least.
FactCheck rating: 4
(high because it's a virtually-impossible-to-verify figure, rather than necessarily being wrong)
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The lower end of the scale indicates that the claim in question largely checks out, while the upper end of the scale suggests misrepresentation, exaggeration, a massaging of statistics and/or language.
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CCTV in London
CCTV User group
Home office's national CCTV strategy
Written answers, CCTV, 4 March 2008
Department for Business, Enterprise and Regulatory Reform: Business Start-ups and Closures: VAT Registrations and De-registrations (Tables 1d and 4d)
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