AN off duty police officer and his metal detector came to the rescue when a woman lost her diamond engagement ring on a riverbank.

Metal detecting enthusiast PC Derek Sirett was called in after a two-hour search of the reed beds alongside the River Wear in Durham City proved fruitless - and within ten minutes the officer came up trumps.

The 30-year-old woman, who has asked not to be identified, was out walking with her husband and six sons on Sunday afternoon near the former boathouse at Elvet Bridge.

As the day was warm and her engagement ring was becoming uncomfortable, she removed it from her finger - but was horrified to see it slip from her grasp and tumble into the dense vegetation at the side of the river.

After an increasingly frantic fingertip search by the entire family drew a blank, the desperate woman called Durham Police - where control room staff remembered Derek and his hobby.

Despite being on leave and having just walked in the door after a trip to Edinburgh, the Stanley-based officer rushed out with his new £800 metal detector. He met up with the family and within minutes had located the ring buried a few inches down in the mud.

He said: "The standard issue metal detectors which we keep in the custody blocks are not sensitive enough for this kind of work.

"I left the headphones off at first to allow the boys to hear any bleeps we got from the machine. We found an old penny initially and then a ring pull from a drinks can, but the third signal we had turned out to be the ring itself."

The relieved owner now plans to write to the chief constable to express her thanks.

The 39-year-old officer, who joined Durham Force 13 years ago after serving with the Met, has unearthed other buried treasure on behalf of the public, including a Consett man who had lost his wedding ring while planting bushes in his garden last summer.