3. The transfer of possession of a registration plate in consequence of the sale or other transfer of the vehicle to which it is fixed and to which the registration mark which is displayed on that registration plate has been assigned shall be treated for the purposes of Part 2 of the Act as not being an activity which consists in selling registration plates where the seller or transferor, as the case may be, of the vehicle is a dealer in vehicles and—
(a)he has arranged the first registration in the United Kingdom of the vehicle on behalf of the intended purchaser or keeper; or
(b)the registration plate was not fixed to the vehicle by him or on his behalf.