What's the difference between a principal policyholder, a vehicle policyholder and a named driver?

The principal policyholder is the person who entered into the contract of insurance on behalf of themselves, each vehicle policyholder and each named driver. They’re the person who took out the policy and they can then choose who is a vehicle policyholder and who is a named driver.

The vehicle policyholder is nominated by the principal policyholder as being the person who drives the vehicle most often and earns the no claim discount. 

Named drivers are additional drivers nominated by the principal policyholder who are entitled to drive the vehicle under the policy.