A North Yorks farmer has come up with an ingenious invention to help combat farm crime.

Brian Richmond, who farms near Northallerton, developed a device to detect the presence of mobile phones by picking up the emitted signal.

After being burgled several times, Mr Richmond invented the device after learning from the police that most criminals use mobile phones when carrying out their crimes.

Having found existing mobile phone detectors to be ineffective, and with the help of experts from Newcastle University, Mr Richmond invented his own.

A small plastic box including antennae is fixed to a high point on the farm, triggering an alarm in the house if a mobile phone emits a signal within a set radius of the property.

“If the user switches his mobile phone off, there should not be any other phone active in the area,” says Mr Richmond, who farms 323ha (800 acres) of arable land.

“Using a mobile phone detector, rather than a movement detector, means no more false alarms from animals and the wind.

If the detector goes off in the night, the householder will know that it can only be an unwelcome visitor.

He can phone the police without alerting the intruder.”

It has been pointed out to Mr Richmond that criminals will eventually learn to switch off their mobile phones during burglaries.

“That may happen, but it will take years and the lack of communication would seriously hamper the burglars’ ability to enter properties undetected,” he counters.

The True Alarms system will be commercially available early next year, and Mr Richmond expects units to cost less than 300.

More details from www.truealarms.co.uk, or email info@truealarms.co.uk.