A UK road sign has been puzzling drivers and sparking online debate.

The circular sign, white with a thick black

diagonal stripe, often leaves motorists unsure of its meaning

— even though it appears on the mandatory driving theory test.

The sign indicates the national speed limit. For cars, that

means 60 mph on single carriageways and 70 mph on dual

carriageways or motorways. Drivers of larger vehicles or those

towing trailers must follow reduced limits: 50 mph on single carriageways and

60 mph on dual carriageways or motorways. In built-up areas with

street lighting, the default remains 30 mph unless signs state otherwise.

While some online joke that the sign means “drive as fast as you

like,” safety experts stress that it does not permit unlimited speed.

It simply signals that standard national limits apply, and drivers

must always adjust to traffic, weather, and road conditions.

Road safety groups such as the RAC highlight the importance of

keeping road knowledge fresh, even for seasoned drivers.

Understanding and following signs helps reduce accidents and

confusion, ensuring safer travel for everyone on the road.