Prince Philip, aged 97, emerged largely unharmed from the incident on the A149 near the Sandringham estate in Norfolk, which saw his Land Rover collide with a car carrying two women and a baby. One of the women suffered a broken wrist.

The cause of the collision is not yet known, with investigations by Norfolk Police still under way. However the incident has prompted discussion about mature drivers and road safety.

Brake’s director of campaigns Joshua Harris said: “With our ageing population it becomes ever more essential to have robust procedures in place that ensure older drivers are not inadvertently putting themselves and others at risk.

“Fitness to drive regulation should be strengthened with compulsory eyesight testing throughout your driving career and regular health checks for older drivers,” he said, to ensure they are “not unwillingly putting lives on the line when they get behind the wheel”.

But the Royal Society for the Prevention of Accidents’ acting head of road safety Nick Lloyd said: “In the wake of the incident, we have inevitably heard calls for mandatory testing of people of a certain age. This is a red herring – age is a completely arbitrary and unreliable measure for assessing someone’s ability to drive. Statistically, older drivers have fewer accidents than other age groups.”

He added that taking away older people’s ability to drive could have a major impact on their independence, but also urged them to be aware of their driving ability and any health conditions that could have an impact on their safety behind the wheel.

Motoring group the RAC’s road safety spokesman Pete Williams said: “Older drivers tend to restrict their driving as they get older and tend to be aware of their limitations. So many will not drive at night and stick to local, familiar roads.

“Nevertheless it is important that all driver and particularly older drivers have regular eye tests and consider any health issues which may impact their ability to react quickly and drive safely.”

Following the incident – but not thought to be related to it – Norfolk County Council has agreed to reduce the speed limit on two sections of the A149 from 60mph to 50mph. It also plans to introduce road safety cameras along the route, which runs east from King’s Lynn.

The council emphasised that the move was on the table well in advance of the Duke of Edinburgh’s collision. “We have been looking closely into the safety of the A149 for some time,” said chairman of the council’s environment, development and transport committee Martin Wilby.

(Photograph: Jamie McCaffrey and licensed for reuse under this Creative Commons Licence)