What are the rules around older drivers?
When motorists reach the age of 70 in Britain they are required to renew their licence, and must do so every three years thereafter.
A licence can be renewed so long as you meet the minimum eyesight requirement and are not prevented from driving for any reason.
Is the Duke known to be a keen motorist?
The Duke, 97, is no stranger to the driving seat, and has previously been seen with very famous passengers in a Range Rover.
Philip showed the former US President Barack Obama and his wife Michelle the personal touch when he drove them and the Queen to Windsor Castle after the Marine One presidential helicopter had landed close to the monarch's Berkshire home during their visit to the UK in April 2016.
The gesture was akin to picking up guests from the airport, although the journey only lasted a few minutes. Mr Obama looked delighted when he discovered Philip would be driving them.
As the Queen and Mrs Obama sat on the rear seats, the Duke looked composed at the wheel of the Range Rover as it made its way around the castle's quadrangle and stopped outside the sovereign's entrance.
Why has Philip's crash sparked debate?
The AA said car crashes involving older drivers can sometimes lead to calls for tighter rules or even bans.
But Edmund King, AA president, said GP and family advice is more significant than a person's age when it comes to how long someone should keep driving.
Mr King said: "If driving restrictions based on age and safety were introduced we would be more likely to restrict young drivers rather than older drivers.
"Young, predominantly male, drivers are much more likely to crash within six months of passing their test than older drivers within six months of hanging up their keys.
"Older drivers often self restrict their driving by not driving at night and only driving on familiar roads.
"The decision to hang up your keys is a tough one but should be based on personal advice from your GP and family rather than being based on some arbitrary age.
"We all age differently and the car is an essential lifeline for many elderly people."
Are there many people over the age of 90 who still have a driving licence?
Figures from the Driver and Vehicle Licensing Agency in 2017 showed more than 100,000 people aged 90 or over still held driving licences.
The data showed that 248 people aged more than 100 still held valid licences, compared with 100,281 over-90s.
What did the police do after the Duke's accident?
As is force policy, officers from Norfolk Police carried out roadside breath tests on the drivers of both vehicles, which proved negative.
They are now investigating the circumstances.
What advice is there for older people who do give up their driving licence?
AgeUK said such a decision can be difficult but that stopping driving does not have to mean the end of independence or mobility.
The charity said on its website: "If you've decided to stop driving, or been advised to by the DVLA, there are many ways you can get around and there may be help with transport costs.
"You may feel worried about the costs of giving up driving and having to pay for public transport, but if you add up the amount you spend on car tax, insurance, fuel and maintenance you may find that using alternatives work out to be less expensive than running a car.
"Most people find adjusting to life without a car is difficult at first. If you're finding life without a car tough and causing you to feel down, talk to a family member, friend or your GP."