Prince Philip's lucky escape from a car crash that saw the Land Rover he was driving roll onto its side surprised many.

Not just for the fact the 97-year-old Duke of Edinburgh came away from the crash uninjured, but that the almost centenarian was still able to drive.

In Britain, driver's licences expire at the age of 70, and from then on you must renew your licence every three years.

Under the law, motorists must notify the UK's Driver and Vehicle Licensing Agency about any medical conditions that could affect their ability to drive safely.

The Duke has retained his driver's licence, despite experiencing health issues in the past few years.

Most recently in 2018, he underwent a hip replacement — a major surgery — after being in pain for week beforehand.

Both Queen Elizabeth II and her husband still drive. ( Reuters: Peter Summers )

In Australia, the rules are a little more stringent, and there have been calls for them to be tightened further.

Sue and Gary Jenkins' 22-year-old son, Dann, was killed by an older driver while he was riding his motorbike in northern NSW.

The 87-year-old driver, Edwin Jessop, was convicted of negligent driving, but had his nine-month jail sentence suspended due to his age.

Not long before the accident, Mr Jessop had been deemed fit to drive, but an eyesight test afterwards found he needed glasses.

The Jenkins campaigned for a crackdown on the assessment of older drivers, including eyesight tests done by optometrists — not doctors — and peripheral vision tests to rule out dementia.

Sorry, this video has expired Dann Jenkins was a keen motorcyclist.

That's despite NSW having the toughest restrictions on older drivers in Australia. Here are the rules and how they vary across jurisdictions.

NSW

In New South Wales, drivers from the age of 75 must start annual medical assessments to retain a licence.

When you reach 85, in addition to the annual medical examination, you must pass a practical driving test every second year to keep your unrestricted drivers licence.

Victoria

Unlike their neighbouring state, Victoria doesn't require drivers to pass a licence test when they reach a certain age.

Instead, the onus is on drivers to decide when they need to reduce or stop driving.

Retaining a licence in Victoria is determined by a person's behaviour and medical fitness to drive, not age.

If an older person develops a medical condition or disability that might affect their ability to drive safely, they may be required to undergo a medical review.

Queensland

In Queensland, drivers aged 75 and over must carry a valid medical certificate every time they drive.

A certificate is issued by a doctor and must be renewed every 13 months. Unlike in Victoria, being certified as medically fit to drive is mandatory, regardless of whether or not you have a medical condition.

Western Australia

In Western Australia, once you reach the age of 80 you need to undergo an annual medical assessment before you can renew your driver's licence.

Once you turn 85, you might be required to do a practical test if your doctor recommends it — but otherwise it's not mandatory.

South Australia

In South Australia, the State Government sends you a self-assessment form when you reach the age of 75 and every year after that.

The onus is on the driver to fill out the form to the best of their ability, although they can get help from a doctor.

But if your doctor feels you might need help determining fitness to drive, the driver will have to undergo a practical driving test, which is a 30-minute drive.

Tasmania

After you turn 65, your licence can only be renewed for five-year periods.

All drivers are legally responsible to report any medical condition that might affect their driving

In 2011, the State Government scrapped compulsory tests for motorists over the age of 85.

ACT

Drivers in the ACT aged 75 years or older must be annually examined by their own doctor.

NT

The Northern Territory Registrar of Motor Vehicles can request that drivers prove they have the necessary skills and are medically fit to hold a driver's licence at any age.