A staggering number of UK drivers have admitted to regularly doing something that voids car insurance and, more worryingly, could see somebody get seriously hurt. The data comes amid concerns there are too many motorists driving unsafely on our roads.

Churchill said that a huge 10% of drivers who need glasses admit to not wearing them while driving. Not only can this invalidate your insurance policy, but you could cause a crash and potentially harm someone if you don’t have full vision while driving.

As well as this, you could be hit with three penalty points and a £1,000 fine. Further research from Churchill estimates that a million drivers could be breaking a key safety rule every day in the UK- and would fail a 20 metre test.

It is estimated that over one million people are driving with eyesight below the UK legal minimum requirement, Churchill says. They have revealed that some 25% of UK adults have not had an eye test in the past two years – and some 2.8 million people have never had an eye test as an adult.

According to gov.uk, you must be able to read a car number plate made after 1 September 2001 from 20 metres. You can use glasses or contact lenses, if necessary.

As well as this, you need to meet the minimum eyesight standard for driving by having a visual ‘acuity’ of at least decimal 0.5 (6/12) measured on the Snellen scale (again, with glasses or contact lenses, if necessary) using both eyes together or, if you have sight in one eye only, in that eye.

Visual acuity is a measure of the ability of the eye to distinguish shapes and the details of objects at a given distance. You must also have an adequate field of vision – your optician can tell you about this and do a test.

In a sign of how important this is, at the start of your practical driving test you have to correctly read a number plate on a parked vehicle. If you cannot do this, you fail your driving test and the test will not continue. DVLA will be told and your licence will be revoked.

The bad news is that a lot of drivers cannot pass this test. Churchill teamed up with a leading optician to test drivers who have not had an eye examination for more than two years. They found that one in ten were unable to read a number plate from 20 metres, the minimum legal requirement.