I have read much of the HSE guidance covering tractor safety and that seat belts are to be worn when there is a risk of overturning etc. I know that if fitted they must be worn but how about if they are not fitted and it isn't practical to fit one - can that tractor still be driven on public highway? I'd just like to know the legal position regards this.

What is the age of the tractor? I see many older tractors still in use which aren't fitted with cabs or roll protection. I certainly wouldn't want to be strapped into one of those.