A CCTV camera is not to blame for immobilising cars in King Street.

Radio engineer Gordon Adams said cheap car radio receivers were more likely to be causing the problem.

"It's not magic," he said. "It's radio transmissions that do it.

"In the car there is a receiver and - if it is a cheap one - it can be affected by other signals." Over the past month drivers have complained about being locked out of their cars after parking near Stephen Edwards Electrical.

A Greater Manchester policeman's Volvo was immobilised, a businessman's alarm sounded for nearly an hour and one woman's car was eventually towed away.

All had complained that the automatic key fobs for their LandRovers and Audis would not work. They thought a nearby CCTV camera could be to blame, but Mr Adams, who has helped police with radio transmitter inquiries, said there was no equipment in a camera that could cause the problem.

"I think it is coincidence and people just look for the nearest thing to blame," said Mr Adams, of Ash Grove.

Yesterday (Tuesday) the Guardian reported the problem to Ofcom which has received similar complaints elsewhere. It was not clear whether the watchdogs would investigate the problem, but they told drivers to speak to their car dealers.

Mr Adams said Knutsford's taxi drivers and police could be unwittingly affecting the parked cars. He said their radio transmissions could be interfering with the cars' receivers. "It's not their fault and they will not know if they are causing it," he said.