We've built up a NCB of over nine years with the same insurer on one car. Recently we acquired a second car and insured it with the same insurer, who in its advertising promises to link the policies and discount the second vehicle. However, they refused to allow a NCB discount on the basis that a NCB is only valid on one car. While I reluctantly accept that this appears to be industry standard practice, I find this unfair and unreasonable. I wonder if you can explain to me why this is the case.