Motorists are being warned to keep sunglasses in their car, even when it's freezing cold outside.
It's not a legal requirement to wear sunglasses in bright conditions, but you could still be considered by police to be "driving without due care and attention" due to Rule 237 of the Highway Code. The "Hot Weather" section of this law states that drivers need to slow down or pull over if they are "dazzled by bright sunlight", which would indicate that drivers should wear glasses on a sunny day.
Although glare problems persist all year round, during the winter it's particularly noticeable because the sun is low in the sky. While it may be cold, this winter sun can pose a real hazard to drivers as the glare can temporarily blind drivers.