Yes, but under certain conditions.
The UK Road Vehicles (Construction & Use) Regulations 1986 Act details the legality of window tinting in the UK and specifies the minimum levels of light that must pass through the windscreen and front passenger windows.
The Act states:
You could be stopped and fined Basically, you are giving the police a reason to stop your vehicle. If it is considered dangerous or unsafe to drive, you could even be given a prohibition order until the tint is removed.
You will be required to remove the film (which is expensive) and return to the required police station confirming and demonstrating that your car now conforms to legal status.
If you cause an accident and it can be proved that the tinted windows impaired your vision, you are very likely to get part or full blame - even if the circumstances were not directly your fault
Insurance companies are always looking for a reason not to pay out on a claim. If they validate that your vehicle has broken the tinting laws you will be deemed as being at fault - which in essence means your insurance is invalidated! This means that you will be looking at not only paying for costs of your own vehicle, but also that of the third party vehicles or property.
We are not trying to scaremonger here, but to see some examples of those who have fallen foul of these laws, please check the Internet!