Nine cameras with the new speaker system have been set up at the Kingsway trading estate near Wilton, but there are already plans to use it elsewhere.

The system is monitored from a centre in Chippenham - 40 miles away - and the idea is to stop crime before it takes place.

One local businessman, Neville Moody of Moody's Removals, told the BBC: "There have been several disturbances on the estate.

"This system is one way of controlling the problem and letting traders sleep at night."

Sergeant Nick Cane, of Wiltshire Police, added: "The speaker system does make a difference: it reinforces the CCTV system and the message that would-be intruders will be captured."

A school in Stroud, Gloucestershire, has already expressed interest in using the system to protect its premises.