People have only just found out what the H on lampposts means

It doesn't mean higher or lower.

Thanks to the holy grail of TikTok, a video explaining what the bright yellow signs with a large black H on them actually mean.

South Yorkshire Fire posted a now-deleted-video on the platform, saying: "POV: You’ve walked past these small yellow signs your whole life."

But it was today you realised, finally, after all these years, they are there to tell firefighters where the hydrants are."

That's right, it's just a handy tool for the fire crew to know where the water supply is.

While a lot of us paid attention in school, many others admitted to not having a clue, with one person commenting: "Well I learnt something new today thank you!"

Someone else added: "I never knew. Everyday is a school day thank you."

A third wrote: “I used to think it was H for helicopter landing", while others asked what the numbers meant above and below the H, with one explaining: “Top is size and bottom is the distance from the sign.”

Using the sign in the video as an example, someone else added: “It means fire hydrant 100mm connection and it’s within 10 metres of the sign.”

There you have it.