Little-known sunglasses rule could catch British drivers out this summer

A glimmer of sunshine and the whole country is in shorts and flip flops, eh?

Seeing as though the Great British summertime is unpredictable, to say the least, we've got to make the most of it while we can, but you might have to give some of your accessories for the warm months a miss while driving.

Yes, having the wind blowing through your hair with the windows down and sunglasses shielding your eyes from the blinding rays is something we all look forward to each year.

But chasing a Grace Kelly-esque moment in the car might land you in a spot of bother - and impact your funds for the beer gardens your most likely going to be living in throughout summer.

Brits have been warned to think twice before sliding their shades on and getting behind the wheel, as drivers can be slapped with a hefty £5,000 fine if their aviators aren't legal.

All pairs of sunglasses in the UK are marked and labelled with a category number which refers to the tint level they have, and these digits will also let you know whether they are safe to drive in or not.

Just as you can't have tinted windows which are too dark on your car, you can't have shades which are too dark either.

The tint levels go from lightest to darkest and are ranked from zero to four in reference to the strength of the lens and the time of day that they are best worn.

The majority of shades will likely be in 'category two', meaning they have a slight tint and will transmit between 18 percent to 43 percent of light - and that they are suitable to whip your car around in.

You might look the part in dark shades, but your fashion choice could land you in big trouble. (Getty Stock Images)

But at the other end of the spectrum, 'category four' sunglasses have an extremely dark tint, while transmitting just three to eight percent of light - so although you might look the part, you can't don them while driving.

If your shades are in this tint range, they should also have come with a label (by law) which explains that they are not suitable to use while driving or on the roads.

With that in mind, the AA recommends choosing one of two types of sunglasses - fixed or variable.

Variable lenses react to the light that is coming in and chance the density of their tint accordingly, but the AA advises getting glasses that react to visible rather than UV light, as windscreens filter out UV.

Fixed lenses remain at the same level of tint regardless, which is fine, so long as they're not too tinted.

But while you're worrying about the tint on your lens, don't forget that wide side arms aren't good for driving either - as they can block your peripheral vision and therefore can impact your ability to be in control of a motor.

Make sure your sunglasses are legal to wear while driving before setting off. (Getty Stock Images)

Drivers are allowed to wear shades though, as rule 237 of the Highway Code explains that motorists should wear them to protect their eyes on the road, otherwise you have to slow down or pull over when dazzled by bright sunlight.

Just be careful when you're sunglass shopping that you don't go for the really dark look - as you could land a £5,000 fine.

If you are found to be driving with inappropriate eyewear - which poses a risk to yourself, pedestrians and other road users - you could face charges for dangerous driving.

Those found guilty face penalties including up to 11 points on their driving licence, five years in prison and unlimited fines - which are capped at £5k in Magistrate’s Court.

Greg Wilson, Founder and CEO of Quotezone.co.uk, said: "Any driver wearing inappropriate sunglasses could be subject to a dangerous driving charge - which potentially comes with hefty fines, penalty points and even prison time.

"It’s your responsibility to make sure your vision isn’t compromised, if you don’t protect your eyes properly from the sun and you have an accident, you could invalidate your car insurance."