Car insurance no claims bonus for second driver

Also called a named driver no claims bonus, it's the discount you can get if you're insured as a named driver on someone else's policy and haven't claimed.

We are able to offer a mirrored no claims bonus to our second car policies. Mirrored no claims discount means that for drivers who have earned no claims bonus (or “NCB”), on their insurance policy for one vehicle, under certain conditions they have the option to use that NCB on a vehicle.

This is not the same as transferring your no claims bonus from one vehicle to another. With a mirrored NCB, you effectively enjoy the discount on both vehicles at the same time. What if all cars have different renewal dates?