What is Thatcham?
A clear guide to Thatcham vehicle security categories - alarms, immobilisers and stolen vehicle tracking - and how they affect your insurance.
What is Thatcham Research?
Thatcham Research is the UK motor insurance repair research centre. Founded in 1969 and funded by the insurance industry, it independently tests and certifies vehicle security products to a consistent, published standard.
Insurers use Thatcham categories to assess the risk of a vehicle being stolen. A Thatcham-recognised device can help reduce your premium, and on higher-value vehicles a specific Thatcham category is often required as a condition of insurance.
Scorpion Automotive is a Thatcham-recognised manufacturer and has been designing and building vehicle security in the UK since 1973. Our products map directly to the categories explained below.
Thatcham security categories explained
Thatcham categories fall into two groups: electronic security (alarms and immobilisers) and stolen vehicle tracking. Here is what each one means.
Alarms & Immobilisers
Alarm + Immobiliser
The most comprehensive electronic security. Combines a full alarm with an electronic engine immobiliser.
- Perimeter detection
- Ultrasonic / tilt sensing
- Electronic immobilisation
- Battery back-up siren
Best for: Prestige, performance and high-value vehicles where insurers demand the highest electronic protection.
Immobiliser only
Electronic engine immobilisation that prevents the vehicle from being started or driven without the correct authorisation. No alarm.
- Electronic engine immobilisation
- Automatic arming
- No audible alarm
Best for: Vehicles that need a Thatcham-recognised immobiliser but do not require a full alarm.
Immobiliser upgraded to Alarm
A Category 2 immobiliser upgraded to Category 1 status by adding a Thatcham-recognised alarm. A common, cost-effective aftermarket route to Category 1 protection.
- Category 2 immobiliser base
- Added Thatcham alarm
- Uses original or added remotes
Best for: Owners who want Category 1 level cover added to a vehicle that already has an immobiliser.
Stolen Vehicle Tracking
Stolen Vehicle Tracking
A tracking device that is notified or activated by the owner. It alerts on unauthorised movement so the vehicle can be located and recovered.
- GPS / GNSS location
- Owner-notified alerts
- Movement alerts
- Secure monitoring support
Best for: Owners wanting recovery-grade tracking and a lower tracking tier than S5.
Tracking + Driver Recognition
The highest tracking tier. Adds Automatic Driver Recognition (ADR) tags so the system detects if the vehicle moves without the driver tag present, with 24/7 monitoring and remote immobilisation options.
- Everything in S7
- Automatic Driver Recognition (ADR) tags
- 24/7 monitoring
- Remote immobilisation options
Best for: Prestige and high-theft-risk vehicles where insurers specify the highest tracking standard.
Note on naming: Thatcham replaced the older CAT 5 and CAT 6 tracking labels with S5 and S7. S5 (formerly Cat 5) is the highest tracking tier and sits above S7 (formerly Cat 6).
Thatcham categories compared
| Category | Type | What it provides |
|---|---|---|
| Category 1 | Alarm + Immobiliser | Full alarm with perimeter and ultrasonic/tilt sensing plus electronic immobilisation - the most comprehensive electronic security. |
| Category 2 | Immobiliser only | Electronic engine immobilisation with no audible alarm. |
| Category 2>1 | Immobiliser upgraded to alarm | A Category 2 immobiliser upgraded to Category 1 by adding a Thatcham-recognised alarm. |
| Category S7 | Tracking (formerly Cat 6) | Owner-notified stolen vehicle tracking that alerts on unauthorised movement. |
| Category S5 | Tracking + ADR (formerly Cat 5) | The highest tracking tier - adds Automatic Driver Recognition tags, 24/7 monitoring and remote immobilisation options. |
Why Thatcham categories matter
Thatcham approval is about more than a badge - it directly affects your insurance, your cover and your ability to recover a stolen vehicle.
Insurance premium reductions
A Thatcham-recognised device is independently proven, which insurers can reward with lower premiums compared with an unprotected vehicle.
Insurer requirements
Many insurers require a specific Thatcham category as a condition of cover on prestige, performance and high-theft-risk vehicles.
Independent proof of quality
Thatcham testing is carried out independently and funded by the insurance industry, so approval is genuine third-party validation of the product.
Aids police recovery
For tracking products (S5 and S7), a monitored device helps locate a stolen vehicle quickly and supports the police in recovering it.
How Scorpion maps to the Thatcham categories
As a Thatcham-recognised UK manufacturer, our security range covers every category from alarms and immobilisers through to the highest tracking tier.
S-Series Alarms
Our S-Series alarm range covers the alarm and immobiliser categories. The S30 provides Category 1 protection, while the S32, S34 and S37 offer Category 2>1 upgrade options.
Explore S-Series Alarms
X-Series Immobiliser
The X-Series is a CAN Bus immobiliser that defends against key cloning and relay attacks, delivering electronic engine immobilisation for your vehicle.
Explore X-Series
Scorpion Defender & ScorpionTrack S5 / S7
Scorpion Defender combines a ScorpionTrack tracker with an alarm or immobiliser. ScorpionTrack S5 and S7 devices provide Thatcham stolen vehicle tracking with 24/7 monitoring.
Explore Scorpion DefenderLooking for S5 or S7 stolen vehicle tracking? Visit ScorpionTrack.com for our full tracker range.
Thatcham frequently asked questions
Does a Thatcham alarm reduce insurance?
A Thatcham-recognised alarm or immobiliser can help reduce your insurance premium, because it is independently tested and proven to lower the risk of theft. The exact saving depends on your insurer, vehicle and policy, and on some higher-value vehicles a Thatcham-approved device is required before cover is offered at all.
What is the difference between S5 and S7?
Both S5 and S7 are Thatcham stolen vehicle tracking categories, and S5 is the higher tier. S7 is a tracking device that is notified or activated by the owner and alerts on unauthorised movement. S5 adds Automatic Driver Recognition (ADR) tags, so the system detects if the vehicle is moved without the driver tag present, alongside 24/7 monitoring and remote immobilisation options.
Do I need Thatcham approval for my insurance?
It depends on the vehicle and the insurer. Many insurers require a specific Thatcham category, such as Category 1 or an S5 tracker, as a condition of cover on prestige, performance and high-theft-risk vehicles. For other vehicles it is not mandatory, but fitting a Thatcham-recognised device can still reduce your premium. Always check your policy documents or ask your insurer.
What is Category 2>1?
Category 2>1 is a Category 2 immobiliser that has been upgraded to Category 1 status by adding a Thatcham-recognised alarm. It is a common, cost-effective aftermarket route to Category 1 level protection, and the alarm can usually be operated using the vehicle original remotes or added remotes.
What replaced the old Cat 5 and Cat 6 labels?
Thatcham replaced the old CAT 5 and CAT 6 tracking labels with S5 and S7. S5 is the direct replacement for the old Category 5 and remains the highest tracking tier, while S7 replaces the old Category 6. S5 is higher than S7.
Not sure which Thatcham category you need?
Talk to our team about the right Scorpion alarm, immobiliser or tracker for your vehicle and your insurance.