It is, alas, not unheard-of. Car thieves target car sellers, on the grounds that it is one of the few times they can get close to a car owner's keys without raising suspicions.

On one recent occasion, the thieves simply jumped the seller of a BMW M3, grabbed the keys and made off with the car. Another technique is for the thief to ask for a test drive, take the keys and drive off while the seller is still on the pavement, about to get in to the passenger seat. When a prospective buyer asks for a test drive, make sure you are sitting in the car whenever the keys are in his or her hands. That applies at the end of the test drive as well – a thief only needs you outside of the car for one second while they have the keys.

The good news is that the BMW case ended well. It was fitted with a Tracker and the owner immediately alerted the police. Within an hour, the vehicle was located in a lock-up in Essex, which also contained two stolen Ford Transit vans, a motorcycle, a Nissan Skyline and numerous other vehicle engines.

Adrian Davenport, Police Liaison Manager for TRACKER said, "This is a tremendous result for the Police and has led to them taking action against a local crime team that has been causing a lot of problems across the region. Luckily, this is a rare occurrence and in this instance the seller wasn't badly hurt, but sellers should be careful when showing their car to prospective buyers."