Topic 1 of 14 · Mirrors and blind spots
Mirrors, blind spots and the order you do things in
Why the mirror check comes before the signal, what your mirrors cannot show you, and the shoulder check that fills the gap.
By the end of this lesson
- Apply mirrors–signal–manoeuvre in the correct order, and say why the order matters
- Describe what a blind spot is and where yours are
- Decide when a shoulder check is needed and when it is not
What you need to know
There is a routine, and the order is not arbitrary.
Mirrors, signal, manoeuvre.
You check what is around you, then you tell people what you intend to do, then you do it. Reverse the first two and your signal is announcing a decision you have not yet made.
Check your mirrors before you:
- signal
- change speed, including slowing down
- change direction or lane
- open a door
What mirrors cannot do
Your mirrors cover most of the world behind you, but not all of it. The area over each shoulder — roughly beside and slightly behind the car — appears in neither the interior mirror nor the door mirrors. That is your blind spot.
It is not a small area, and it is exactly where a motorcyclist overtaking a queue, or a cyclist filtering up the nearside, will be.
The fix is a shoulder check: a quick glance, about half a second, before you commit. Use it before:
- moving off from the kerb
- changing lane
- turning where someone could be alongside you
Use it before you signal, so the signal reflects what you have seen.
See it on the road
You are slowing to turn left into a side road.
As your speed falls, a gap opens between your car and the kerb. From behind, a cyclist reads the situation as “that car is slowing down, I can get past” — and moves into it. Your mirror check happened before you started slowing, when the road behind was empty.
This is the single most common serious collision between a car and a bicycle. The second mirror check, immediately before the turn, is what prevents it.
Why it matters
Under the hierarchy of road users, the driver of the vehicle that can do the greater harm carries the greater responsibility. A cyclist and a car meeting at walking pace is a bad day for the cyclist and a scratch for the car.
That is why the routine puts looking first, every time — not because the rule book says so, but because you are the one with the ability to prevent it.
The habit worth building
Say it to yourself for the first few weeks:
- Mirrors — interior first, then the one on the side you are moving towards.
- Shoulder — if anything could be alongside.
- Signal — now that you know it is safe.
- Manoeuvre — smoothly, still watching.
Within a month it stops being a list and becomes the way you drive.
The three things to remember
- Mirrors before signalling, before slowing, and before any change of direction — a signal given before you have looked is a guess.
- Mirrors cannot show the area over each shoulder, which is exactly where an overtaking cyclist or motorcyclist will be.
- As you slow for a left turn, a gap opens on your nearside. Something will fill it.
⚠ The common mistake
Signalling first and looking afterwards. It feels efficient and it means your signal is a statement of intent rather than a decision you have actually made.
On the road
You slow to turn left into a side road. A cyclist, seeing your car slow down, moves up your nearside. Your mirror check happened ten seconds ago, when they were behind you.
Check you have it
Answer these without scrolling back up. Retrieving something from memory is what makes it stick — rereading feels productive but does far less.
Preparing your questions…
Sources checked for this page
- The Highway Code — Rules 159, 161 and 182
We summarise official guidance in our own words. Where the rules matter legally, check the official source. This site is not affiliated with DVSA.