Currently in the UK there is no legal maximum age limit for drivers.
Instead of a set age limit for drivers, as some countries employ, other factors are taken into account to assess your ability to drive.
Health issues are the most common reason older drivers are no longer permitted to drive, with the increased risk of failing eyesight, cataracts, and cognitive impairment illnesses like Alzheimer's disease being more prevalent in older drivers.
Aside from medical conditions, there are limitations to your driving ability that you should also take into account, such as slowed reflexes, increased confusion in stressful situations, reduced mobility and stiff joints.
It can often fall on the driver themselves to assess their own driving ability to ensure they are not putting themselves and other road users at risk.