A UK motorist recently sparked online debate by claiming that “99% of drivers” don’t recognize a common road sign seen nationwide. The sign is circular, white with a thick black diagonal stripe, and often misunderstood or misused despite being part of the mandatory theory test.

Known officially as the national speed limit sign, its meaning often confuses drivers. On Reddit, users joked it meant things like “national drifting zone” or “go as fast as you want.” Many drivers seem to forget its real purpose once on the road, sometimes speeding or overtaking carelessly where it appears.

In fact, this sign indicates that the national speed limit applies from that point onward. It overrides any previous speed restrictions, such as temporary zones or lower limits.

The actual national speed limit depends on the road type and vehicle: on single carriageways, cars can go up to 60 mph; on dual carriageways and motorways, 70 mph. Vans and vehicles towing trailers have lower limits: 50 mph and 60 mph, respectively. In built-up areas with street lighting, the default speed limit is 30 mph for all vehicles.

Despite the sign’s clear legal meaning, drivers should use discretion. Weather, road conditions, and traffic often require slower speeds. The RAC stresses that safety and common sense always come first.

This confusion shows the need for ongoing road education well beyond the driving test.