SCHOOLS ARE installing detection systems in classrooms, exam halls and changing rooms to combat pupils’ pervasive use - and misuse - of mobile phones.

When Tendring technology college in Essex installed two detectors in its exam halls in January, supervisors discovered about 20 phones among 100 pupils.

Melanie Bowler, a teacher at Tendring, said: “The kids hate the detectors.

We love them.”

Adroit Global Technology, which manufactures the pound;150 devices, said it had sold them to more than 20 schools in the UK.

The detectors discreetly alert teachers that a mobile is switched on. Or they make a recorded loudspeaker announcement. “We have detected your mobile phone,” an authoritative voice booms. “Turn off your mobile immediately.”

Of 4,500 pupils reported to the Qualifications and Curriculum Authority for exam cheating in summer 2005, 1,100 were found to have smuggled in mobile phones.

Stephen Lee, a director of Adroit, said detectors were also being installed in changing rooms to stop pupils taking and distributing photos of other pupils.

Schools have been told they cannot use technology that actually blocks mobile phone calls and text messages: that would be unlawful under the Wireless and Telegraphy Act. But they are allowed to detect phone use.

“It is illegal to block mobile phone activity,” said Mr Lee. “That is why we’ve gone for a system that doesn’t interfere with the signal.

“By adapting the software, we could collect the mobile phone number that has been detected and send an automatic text message telling them (the owner) to switch it off. But even that might be a civil liberties issue, and we’re not going there at this stage.”

Les Glasby, assistant principal at Tendring, said that before the alert system was installed, his school had had to report a few pupils who were caught with mobiles to exam boards. Now there are red warning signs hanging in their exam halls.

The 20 pupils in the January mock exam were astonished to have their mobiles confiscated.

“They were so amazed. They didn’t believe it,” Mr Glasby said. “If it’s going to stop students being stupid and getting banned, that’s all for the better.”