A man selling a car had a nasty surprise when a potential buyer stole the vehicle during a test drive.

The seller had arranged to meet the customer in Rossington Avenue, Borehamwood on January 2 shortly after 3pm.

He arrived in the white Mercedes hatchback, and showed the customer around the vehicle.

But he had left the engine running, and as he was walking round to the passenger side the customer moved into the driver's seat, locked the doors and sped off.

Inspector Graeme Walsingham, from the Hertsmere Local Crime Unit, said: “Sadly not everyone is honest and some people will take advantage of those who advertise their vehicles for sale and then arrange to meet a potential buyer.

"Enquiries are ongoing to locate the offender and vehicle and I would urge anyone who believes they have seen this car since it was stolen or may know of its whereabouts to please contact police."

The vehicle's registration is BV62 TVJ.

Anyone with information should call 101, quoting crime reference number J1/18/15 .

Hertfordshire Constabulary offers the following crime prevention advice when selling your vehicle:

• When taking a potential buyer on a test drive take someone else with you.

• Keep a charged mobile phone in your pocket in case you need to alert police.

• Stick to a route you know that is close to home and let others know the route you are taking and when to expect you back.

• If in any doubt do not allow anyone else to drive your vehicle.

• Make sure any test driver has a valid driving licence and suitable insurance cover. You could be liable for any accidents they may have.

• To avoid buyers being left alone (and potentially driving away) with your vehicle, keep hold of the keys at all times and avoid leaving them in the ignition.

• Ensure you have removed your house keys from your car keys.

• Never hand over the vehicle keys or documentation until your bank has confirmed the full value of the vehicle has cleared into your bank account.