A chief constable has defended the use of CCTV surveillance cameras by saying they helped Cambridgeshire Police to locate a missing girl recently.
There are up to 4.2m CCTV cameras in Britain
Julie Spence, who heads Cambs Police, said cameras were a vital police tool.
Colin Langham-Fitt, acting chief constable of Suffolk police, has questioned whether CCTV contributes to "ongoing erosion of civil liberties".
Hampshire deputy chief constable Ian Readhead said he feared an "Orwellian" society with cameras on every street.
Mrs Spence has joined a debate on the use of surveillance cameras in public areas and on Sunday she highlighted the value of CCTV.
Vital police tool
She pointed to a recent case in which a missing 11-year-old girl was quickly located in Cambridgeshire.
"Within 24 hours we had managed to track the movements of the missing girl and identify that she was with someone else at the time," she said.
"This proved invaluable to the inquiry team and the vital public appeals we needed to make.
"We had some excellent images of the girl. CCTV has helped the police considerably on a range of matters and this is one example of it."
Mrs Spence added: "We don't sit down and monitor what people are doing all of the time. While I understand there is a debate about the 'surveillance society', let's not lose sight of the fact this is a very vital tool to the police.
"Having CCTV saves hours of police officers' time and is very effective."
But Mr Readhead, of Hampshire Police, has raised concerns over the use of CCTV.
He told the BBC's Politics Show: "I'm really concerned about what happens to the product of these cameras, and what comes next?
"If it's in our villages, are we really moving towards an Orwellian situation where cameras are at every street corner?
"And I really don't think that's the kind of country that I want to live in."