Thatcham is the governing body responsible for setting vehicle security standards. In 1993 the British Insurance Industry gave them the task of testing the effectiveness of security devices. Since then they have tested hundreds of alarms and immobilisers for after sale fitment. Once deemed to be good enough and effective enough to be Thatcham compliant, these systems become 'Thatcham Approved' and appear on a quarterly publication - Thatcham Vehicle Security National Listing.

There are 3 relevant approval categories:

Thatcham Category 1 (Cat 1) - This is the most comprehensive category and is for systems that comprise both an alarm and an immobiliser. fitting a 'Cat 1' will qualify you for the maximum insurance discount.

Thatcham Category 2 (Cat 2) - This is for immobiliser systems only. It is the minimum requirement for most insurance companies. An immobiliser is probably the most important part of any vehicle security system.

Thatcham Category 2>1 - This means that if you already have a 'Cat 2' approved immobiliser fitted to your car, you can upgrade it to full 'Cat 1' status with a 2>1 alarm.

Therefore, if your insurance company specifies that you must have a 'Cat 2' for example, then they require you to fit an immobiliser which has been approved by Thatcham.

In order to be effective and safe it's also vitally important that alarms and immobilisers are fitted properly to your car. Your insurance company will require a 'VSIB certificate', this tells them that the security device has been fitted to the high standard set by the VSIB (Vehicle Systems Installation Board). For more information on VSIB you can visit their website here VSIB website