Brits convinced '99% of drivers' have no idea what this road sign really means

Knowing the Highway Code is critical if you want to be able to legally drive on any road around the United Kingdom. But what about remembering what the Highway Code told you, years after passing those fabled theory and practical tests?

Yes, we're talking about road signs and making sure you know what they mean for both practical and safety reasons.

After all, if you didn't know what the number '30' on a white background in a red circle meant, you're going to get in a whole lot of legal trouble and potentially endanger other people on the road and pavements.

Learning these signs means you're telling the bosses at the DVLA that you're safe to drive. Pass your test on them and you're halfway there, with just the practical test to go.

But any ordinary driver is likely lying if they say they can remember every sign in the Highway Code. And over on Reddit, one motorist has vented about one road sign in particular. According to them, they reckon that many of us wouldn't be able to understand what it means at all.

Go on then, what's the sign?

There's thousands of them across the roads up and down the United Kingdom.

Incredibly common, really. A white circle with a black strip through it at a 45 degree angle.

Taking to Reddit, the driver wrote: "I'm convinced 99 percent of drivers don't know what this sign means."

So you think you know what it means? (Getty Stock Images)

What does the white circle and black strip mean?

To many it might be obvious. Or so you think.

Responding to the original post, Redditors have had a good few attempts at guessing at what the sign means.

Rather tongue in cheek, one Reddit user posted: "National speed limit, but what that limit is depends on what you’re driving. For example if you’re driving a BMW it’s 100mph and excuses you from using indicators."

Another replied to the thread saying: "There's a road near me with this sign and if you're averaging more than 30mph down it you're either a complete plank or suicidal."

A third shared a rather worrying tale: "One of the girls at my old hairdressers genuinely thought it meant 'go whatever speed you want'."

Safety first, not speed (Getty Stock Images)

National speed limit - but not something you should always go at

According to Gov.uk, the sign means you're now on a stretch of road where 'the national speed limit for the type of road and class of traffic applies'.

The RAC website says similar. But it also offers some much needed clarity. Explaining that the white circle and diagonal stripe 'tells you that the national speed limit applies on the upcoming stretch of road', it adds that it also 'supersedes any previous speed limit signs you may have had to adhere to, such as passing through temporary roadworks'.

Critically, though, safety is more important than speed. It adds: "Of course, even when the national speed limit applies, it might not always be safe to drive at that speed, so use your common sense on this."

On a single carriage this would mean there is a 60mph limit for cars and 50mph for vans and other large vehicles, as well as cars with a trailer. Dual carriageways carry a 70mph limit for cars and 60mph limit in line with the same vehicles on a 60 road.

But the law clearly states that safety is more important than definitely travelling at these top speeds. And with many of the roads having 60mph limits being narrow country lanes, you'd be a moron to travel that fast anyway.