When you brake suddenly without checking what's behind you, you're making a decision blind. The driver behind might be travelling closer than you think, or braking from a higher speed. A quick glance in your interior mirror before reducing speed costs you less than a second — and it's a requirement the DVSA examiner is specifically watching for.
By the Numbers
The MSM (Mirror–Signal–Manoeuvre) routine is one of the core competencies DVSA examiners assess throughout every UK driving test. Failing to apply MSM — particularly skipping the mirror check before slowing — is recorded as a 'Mirrors — change speed' fault. According to DVSA's published statistics (gov.uk/government/statistical-data-sets/car-driving-test-data-by-test-centre), mirror faults appear consistently in the top 10 most recorded minor faults across all UK test centres.
Why UK Roads Make This Critical
UK driving culture involves closer following distances than many other countries. Even careful drivers often maintain gaps that would be considered too short by the Highway Code's two-second rule. When you check your mirror before braking, you can choose progressive braking over sudden stops — giving the driver behind time to react.
Mirror, Signal, Manoeuvre — In That Order
The MSM routine is the foundation of UK driving. Mirror comes first, before any signal or manoeuvre. Reducing speed is a manoeuvre. So the sequence when slowing for a hazard, junction, or stop is: rear mirror → (signal if appropriate) → begin braking. Reversing the order — braking first, then checking — is the fault pattern examiners see most.
When to Check
Check your rear mirror before:
- Slowing for traffic lights
- Approaching a pedestrian crossing
- Pulling over to park
- Reducing speed before a sharp bend
- Slowing behind slow or stationary traffic
Instructor's Tip
If the car behind is very close, you can adjust your braking to be more gradual rather than firm — giving them more time to respond. You can only make that judgement if you've looked in the mirror first. The rear mirror check doesn't just satisfy the examiner; it genuinely helps you drive more safely.
Frequently Asked Questions
- If there's no one behind me, does the rear mirror check still matter?
- Yes — you must still check. The examiner records whether the check was made, not whether someone was there. You cannot know it's clear until you look.
- How often should I check my rear mirror generally?
- As a general guideline, every 5–8 seconds on open roads. Before every braking, turning, or accelerating action.
- Does this apply to emergency stops?
- In the emergency stop exercise, the examiner will tell you to brake as quickly as possible — do not check your mirror before the emergency stop. That exception aside, all normal slowing requires a mirror check first.