A UK motorist recently sparked debate online by claiming that “99% of drivers” don’t recognize a common road sign seen across the country. The sign in question is circular, white with a thick black diagonal stripe, and is often misunderstood or misused by drivers. Despite being part of the mandatory theory test, it appears that many motorists either forget or misinterpret its meaning after passing.

The sign is officially known as the national speed limit sign, yet its purpose often confuses drivers. In a Reddit discussion, users joked about its meaning, offering humorous guesses like “national drifting zone” or “go as fast as you want.” Others pointed out how in real-world driving, its presence seems to invite speeding or careless overtaking — clearly showing a disconnect between training and practice.

To clarify, this sign means that the national speed limit applies from that point forward. As explained by the RAC, it overrides any previous speed limits, such as those used in temporary zones or lower-limit areas. However, the actual national speed limit varies depending on the road type and vehicle category.

For example, on single carriageways, cars may travel at up to 60 mph, while on dual carriageways and motorways, the limit is 70 mph. Drivers of vans or vehicles towing trailers must observe lower limits — 50 mph and 60 mph respectively on these roads. In built-up areas, with frequent street lighting, the default speed limit remains 30 mph for all vehicles.

Despite the sign’s clear legal definition, drivers must also use discretion. Weather, road conditions, and traffic may require speeds well below the national limit. The RAC reminds motorists that safety and common sense should always take precedence.

This confusion highlights the importance of ongoing road education even after passing the driving test.