Some of these systems are being sold to schools - and it seems likely that not all of the choices are being wisely made. One cash-strapped, vandal-hit Liverpool school is said to have embarked on a drive to raise Pounds 20, 000 for a hi-tech surveillance system, before being advised that something less expensive might do the job.

This story comes from Domineye (UK), a firm which has set out to find a cheap but robust solution to the problem.

The Domineye Pro system keeps costs down, explains marketing manager Melanie Bray, by going for simplicity, and by making use of equipment already in most schools. “You already have televisions and videos, so you don’t need to spend thousands. Our system has just one cable from the camera to the television. ”

There are no revolving, zooming cameras on poles either. A typical installation, such as the one at Fulfen Primary School in Cannock, Staffordshire, consists of a small camera behind an unremarkable dome over the front door. This feeds to two television screens, in the head’s and secretary’s offices. The aim is to keep an eye on who is coming up the path to the door. “I find it very useful,” says head Chris McDonnell. “I’m interested in who’s about to walk in. And if they wander around towards the back of the building we can go out and find them.”

Fulfen’s system is not linked to a recorder, but schools that want out-of-hours surveillance can use a video recorder in long-play mode, recording for eight hours. If this is not long enough, a second recorder can be programmed to pick up when the first one finishes. “You need only look at the tapes if there’s been an incident,” explains Ms Bray.

Because the system is cheap and effective, it can be installed quickly and leaves open the option of going for something more sophisticated later. This was the case at Millwood Primary in Speke, Liverpool, where a Domineye system was put in following a demoralising vandal attack on seven classrooms. “Everyone knows we are protected now,” says headteacher Diane Auton.

The system can be extended with further cameras or more sophisticated recording equiment. Or it can be left to do the kind of simple job it does at Fulfen Primary. Either way, school staff should not make the mistake of buying expensive equipment without taking the advice of the local crime prevention officer, and shopping around.

A simple one-camera installation costs Pounds 199.99. A two-camera set-up is about Pounds 450 and additional cameras are about Pounds 100 each.

Domineye (UK), Domineye House, 18 Rodney Street, Liverpool L1 2TQ.Tel: 0151 708 0101