It takes 1,000 CCTV cameras to detect just one crime, the Met Police has admitted.
The news takes on extra relevance for pubs after reports of several police forces in parts of the country, including Islington, Richmond and Liverpool, objecting to licence applications where venues don't agree to use fit CCTV.
Each case helped by the use of CCTV costs around £20,000, according to the Telegraph, which obtained the information under the Freedom of Information Act.
A Met Police report said: "For every 1,000 cameras in London, less than one crime is solved per year."
Tory David Davis told the paper: "CCTV leads to massive expense and minimum effectiveness. It creates a huge intrusion on privacy, yet provides little or no improvement in security."
The Infomation Commissoner's Officer (ICO) also voiced its concerns about CCTV in pubs earlier this year.
It said: "Hardwiring surveillance into the UK's pubs raises serious privacy concerns.
"We recognise that CCTV plays an important role in the prevention and detection of crime, and can help to reduce crime in areas of high population density, such as city boroughs.
"However we are concerned at the prospect of landlords being forced into installing CCTV in pubs as a matter of routine in order to meet the terms of a licence.
"The use of CCTV must be reasonable and proportionate if we are to maintain public trust and confidence in its deployment. Installing surveillance in pubs to combat specific problems of rowdiness and bad behaviour may be lawful, but hardwiring in blanket measures where there is no history of criminal activity is likely to breach data protection requirements."