Sprita Patel rang in exasperation over groups of kids hanging around her store, Sprita One Stop in Nottingham. It started after she had a ramp with a handrail installed for disabled access. The kids, many of whom she knows and even likes, took to using the ramp as their 'park bench' after hours and broke the handrail.

The police, when persuaded to patrol, came at stupid hours such as 10am when, of course, there were no kids about.

I suggested the cheapest ploy would be to play classical music - very uncool so the kids push off. However, if it's after hours that would not be practical. So I caught up with South Wales company Compound Security Systems, which I first reported on in January this year. It produces the Mosquito device and has sold 1,500 of these high-frequency, ear-piercing noise systems in the UK in the past year and loads overseas.

The Mosquito emits the teenage equivalent of a dog whistle: you can't hear it after you get into your 20s and although it does no harm to those who can hear it, it does their heads in and they move away.

I am still impressed by the enterprise of the first user, Robert Gough, who runs a Spar in Barry, very near the producing company. He told kids questioning the device that it was to keep the birds away in case of Avian flu.
Many local police praise the system and the Association of Chief Police Officers is currently testing it through its Secured by Design programme.

It isn't cheap at £580 for a basic blaster, but as a company spokesman says: "Retailers will spend that on CCTV systems that produce poor-quality images that police say are useless. This does what it says on the box."
I suggested to Sprita that she confers with the Chinese takeaway next door, which is also plagued by the kids, as they could split the cost.

For more information, go to www.compoundsecurity.co.uk.