How old is too old to drive? Or is it all down to the person, not their age?
Prince Philip's involvement in a car crash in his Land Rover Freelander Queen's Sandringham Estate in Norfolk has reingited the debate on the age at which people should stop driving. At present there is no upper age limit, though drivers to have to renew their licences after the age of 70 - then every three years after that.
The Duke of Edinburgh asked if everybody was all right in the aftermath of an accident which saw his car "tumbling" over the road, an eyewitness has said.
Motorist Roy Warne has described how the crash unfolded in front of him as he was driving home on Thursday afternoon.
He immediately went to the aid of passengers, not realising one of the drivers was Philip.
The duke, 97, was driving a Land Rover Freelander, which flipped over after it was hit by another car when he pulled out of a driveway near the Queen's Sandringham Estate in Norfolk, on to a busy A-road.
The woman driving the other vehicle, a Kia, and her female passenger, needed hospital treatment, and there was also a baby in the car.
Mr Warne said he helped the duke get out of his wrecked Freelander through either the sunroof or windscreen after it had rolled all the way over before coming to rest on its side.
The motorist told BBC Radio 4's Today programme: "I was driving home and I saw a car, a black Range Rover, come out from a side road and it rolled and ended up on the other side of the road and there was a huge collision with another car.
"I went to the other car. There was a baby in the back and, with another man, we got the baby out.
"Then I went to the black car to help and realised it was the Duke of Edinburgh."
Asked if Philip was trapped, Mr Warne said: "Yes, he was. I asked him to move his left leg and that freed his right leg and then I helped him get out."
When questioned about what the duke said, he replied: "I can't remember, but it was nothing rude.
"He was obviously shaken, and then he went and asked if everyone else was all right."
Mr Warne said the duke was able to stand and walk immediately after getting out of the car, but he appeared to suggest the duke may have been cut, possibly by broken glass.
"There was a little bit of blood and one of the royal entourage gave me a wipe to wipe my hands," he said.
Buckingham Palace has said that after the accident the duke "saw a doctor as a precaution and the doctor confirmed he was not injured".
Commenting on the circumstances of the crash, Mr Warne added: "I think there's no doubt that it was hit (by the duke's car). That's my recollection.
"I didn't see it come from the side road, I saw it careering and tumbling
across the road and ending up on the other side.
"It would take a massive force and it had rolled on the other side as well."
Asked if he meant that the Freelander had "rolled right over", Mr Warne said: "Yes."
Describing how he helped the duke from his car, Mr Warne told Today: "I think I helped him out through either the sunroof or the front windscreen, but I'm a bit blurred about that."
Mr Warne was still on the scene when the ambulance arrived, but did not hear anyone discussing whether Philip should be taken to hospital.
"I didn't hear any discussion like that, but I was told he was taken to Sandringham House for assessment."
Asked if the duke thanked him, Mr Warne said: "No, but he wasn't being discourteous or anything. He had other things on his mind, I'm sure."
Other eye witnesses have said how Philip, who retired from public duties in 2017 but remains active, was left "shocked" following the accident.
The motorist suggested the duke may have been accompanied by an entourage in another car which is likely to have included police officers.
He told Today: "A lot of people arrived very quickly."
Describing how he helped the occupants of the other car involved, Mr Warne said: "The person in the car behind me also stopped and a passenger from that car actually took the baby in his arms after we had freed it from the baby harness.
"One of them had a broken arm. They were very shaken. One of them was the mother of the child and she was quite upset.
"I think there's no doubt that it was hit (by the duke's car). That's my recollection."
The crash happened at the Babingley crossroads on a stretch of the A149 which runs between the town of King's Lynn and the north Norfolk coast.
It is single carriageway and has a 60mph speed limit.
Concerns had previously been raised about road safety on the A149 near Sandringham.
By coincidence, Norfolk County Council is scheduled to meet on Friday to discuss plans to reduce the speed limit on the road from 60mph to 50mph and install safety cameras.