A sign that gives orders
National speed limit
The national speed limit sign - a white circle with a single black diagonal - does not mean 'no limit'. It means the national limit for that road now applies.
01
What it means
This is the most misread sign on the road. The black diagonal does not mean 'derestricted' or 'as fast as you like' - it means the national speed limit applies from here, and you need to know what that is for the road you are on. For a car: 60 mph on a single carriageway, 70 mph on a dual carriageway, and 70 mph on a motorway (Highway Code Rule 124).
The number is not on the sign - the road type sets it. It usually appears where a lower limit ends, for example leaving a 30 or 40 zone out of a village.
02
Where you'll see it
Rural single-carriageway roads leaving a built-up area, the start of national-limit dual carriageways, and the end of speed-limit zones. On a twisty single carriageway the national limit is 60, but that is a maximum, not a target - bends, hedges and conditions often mean much slower is safer.
03
On your driving test
Two opposite faults come up: treating the sign as permission to speed up hard (especially onto a 60 single carriageway that is actually narrow and winding), and driving so far under the limit that you hold up traffic and hesitate.
Read it as 'the national limit now applies - what is it here, and what is safe right now?' Making confident progress up to a safe speed is a marked skill; so is easing off for a bend.
Often confused with
Quick answers
Does the national speed limit sign mean no speed limit?
No, and this is the big misconception. It means the national limit for that road applies. For a car that is 60 mph on a single carriageway and 70 mph on a dual carriageway or motorway.
What is the national speed limit for a car?
60 mph on a single carriageway, 70 mph on a dual carriageway, and 70 mph on a motorway (Highway Code Rule 124). Vans and other vehicles can be lower.
Why doesn't the sign show a number?
Because the limit depends on the road type and your vehicle. The same sign means 60 on a single carriageway and 70 on a dual carriageway.
Sign artwork is Crown copyright, reproduced under the Open Government Licence v3.0; meanings from the Highway Code (gov.uk).
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