It doesnt apply to dealers as far as Im aware, only to aftermarket plate makers. Basically, anyone who makes up/sells after market reg plates now by law has to put some kind of identification mark and their VAT reg. no on the plate, so that any illegal plates (dodgy fonts, spacing, cloned plates, etc.) can be traced back to the company and they will be fined. This is really a ploy to make it more difficult to find companies willing to make up dodgy plates, illegal or without seeing the V5 first, cos theres more at stake if companies do this. But there will always be the backstreet dealers willing to make up anything you ask them to, and these types of companies wont put their mark on the plates anyway!!