What does the turn left ahead sign mean?
Turn left ahead. This is a mandatory instruction, not a suggestion.
A blue circle with a white arrow curving to the left.
What you must do
Get into position and turn left at the junction ahead.
Where you will see it
Approaching a junction where only a left turn is allowed.
Easy to confuse with: Turn right ahead
The mirror sign points right and means turn right ahead. See the turn right ahead sign.
Test yourself
The theory test asks you to recognise signs like this one. Try the road and traffic signs quiz (with an easy and a hard set), or read the signs revision notes. Source: Know Your Traffic Signs.
Other common road signs
Meaning based on Know Your Traffic Signs and The Highway Code under the Open Government Licence v3.0. The sign image is our own simplified rendering for learning. Always check the current Highway Code on gov.uk. Not affiliated with or endorsed by the DVSA.