The VIN is the unique 17-digit number, which identifies your car from every other car on the road. Thieves recognise that if they steal cars with windows marked using the VIN or registration number, that the glass will have to be removed and replaced if it is to be sold on. Using the VIN is also a useful way of checking that parts of the vehicle match up and can help police to identify the rightful owner.

The windows on most new cars are marked by the manufacturer with a VIN, and sometimes using a special code that they can use to match them to the right chassis.

However, owners of older cars don't have to miss out. Many companies that sell windscreen and car window glass also hold regular free security etching sessions at their branches across the UK and at events organised in conjunction with the police.