Thatcham Vehicle Security Guide – What do the Categories mean?

What is Thatcham?

When researching vehicle alarm, immobiliser & trackers you will have most likely seen the words “Thatcham Approved“,  “Thatcham Accredited” or “Thatcham Category …“.


Thatcham Research is also known as The Motor Insurers’ Automotive Research Centre. They were established with an aim to reduce motor insurance costs whilst setting and maintaining safety standards within the automotive industry.


Thatcham Research test and categorise alarms, immobilisers and trackers, with each category detailing the safety level/features of the device/product.

This is where the term “Thatcham Approved” or “Thatcham Accredited” comes from.


Thatcham separate products into the following groups and give them a security category/classification?

  • Electronic Alarms & Immobilisers
  • Vehicle Tracking & Asset Location Systems (including monitoring centres)
  • Whole Vehicle Marking
  • Locking Wheel Devices
  • OBD Electronic Port Protection


Click here for Thatcham Research Vehicle Security Product Definitions Guidelines


Thatcham Category 1

Electronic Alarms and Immobilisers –

  • The most complex systems available.
  • The immobiliser will isolate at least two vehicle operating systems.
  • Perimeter and ignition detection.
  • Sensors to detect vehicle movements such as tilting or glass breaking.



Thatcham Category 2

Electronic Immobilisers –

  • Same immobiliser specification as Cat 1.
  • The immobiliser will isolate at least two vehicle operating systems.



Thatcham Category 2/1

Electronic Immobilisers & Alarm Upgrades – 

  • A Cat 2 vehicle is retrofitted with an alarm that meets the requirement of Cat 1.



Thatcham Category 3

Mechanical Immobilisers – 

  • A physical device such as steering wheel locks or wheel clamps, that render the vehicle inoperable.
  • Must not be electrical.



Thatcham Category 4

Wheel Locking Devices – 

  • Primarily, locking wheel nuts that either prevent or delay the theft of vehicle wheels.



Thatcham Category 5-7 – No longer in use

From 2019, Category 5, 6 & 7 have been split into two new categories S5 & S7.



Thatcham Category S5 – Superseding previous Category 5 or 6 from 1st January 2019

Post-theft Vehicle Trackers with Automatic Driver Recognition (ADR) – 

  • Online Tracking.
  • Must be able to recognise the Driver of the vehicle, usually through either tag or cards.
  • Movement without these tags will send an alert to the owner of the vehicle.


Thatcham Category S7 – Superseding previous Category 6 or 7 from 1st January 2019

Post-theft Vehicle Trackers without Automatic Driver Recognition (ADR) – 

  • Online Tracking.
  • Does not require ADR tags/cards.
TWA Autoelectrics Building Forecourt

TWA Autoelectrics Ltd

Established 2001

South Wales #1 Independent Auto Electrical & Diagnostic Specialist

Transparent Pricing

At TWA we believe in being open about our pricing, that’s why we display our hourly labour rate below:

Retail – £66 inc. VAT

Trade – £55 excl. VAT