Sorry, this is exactly the point. If I have a Zed (max NCD), premium £500 and buy a BMW 330D (no NCD) and then have an accident with the BMW, are you saying I don't have to declare it to the Zed insurers and my next year's premium will be unaffected assuming they're not mirrored? My company always asks if I've had any convictions or accidents in the last 5/3 years, full stop. Not which car it was in.
Thats just what I was saying, sorry if it wasn't clear enough. In simplest terms. You wouldn't loose your no claims bonus on the Zed with the other policy but you WOULD have to declare you had a claim so they would put the premium up anyway. Hope thats clearer!
In which case, it's the driver who earns the NCD and it should be applied to any car he owns no matter how many. Differences in premium would be the cost to repair and the potential for having an accident ie. horsepower and age of driver.
The driver does earn the NCD and it can be assigned to any vehicle but you cant assign one lot of no claims to 2 or more vehicles at once unless the insurance company specifically allows it for whatever reason.
and your insurance really has sod all to do with cost to repair of the vehicles nowadays. Its more about the millions in compensation someone could claim if you run into them!