Under the United Kingdom Design Registration Act, designs are only registrable if they relate to an article. The term "article" is defined in the statute as meaning "any article of manufacture and includes any part of an article if this is made and sold separately." In a case relating to applications by the Ford Motor Company to register UK designs for a series of components used in vehicles (cars in this case), the House of Lords was called upon to determine the meaning of the definition of "article." Before the case had reached the House of Lords the components in which Ford was interested had been divided into two groups, one group including items such as main body panels, doors, wind screens and the like, all of which were necessarily incorporated into a finished car, and the other group including parts such as wing mirrors, wheels, seats, steering wheels, etc. where a substitution of parts was possible. It had already been agreed that the second group was registrable and the appeal focused only on those parts which when used "form part of and contribute to the overall shape and appearance of the vehicle."

Ford argued that since parts such as body panels were made separately from the entire car and could be sold separately from the entire car then they must meet the requirements of the definition of "article" in the statute. The House of Lords disagreed and read the definition as meaning "if the part is to be made and sold separately". That is to say there must be some market for the part in question independent of the larger article of which it forms a part. The House of Lords decided that the "purpose of the words of the definition was to distinguish between on the one hand an item designed for incorporation, whether as a spare part or as an original component in a particular article or range of articles made by the manufacturer of the component and, on the other hand, an item designed for general use, albeit aimed principally at use with the manufacturer's own artifacts."

In the present case the parts in question were such that they could not in the House's view have been "conceived as items of commerce on their own" and hence were not registrable. Under Section 51 of the Copyright, Designs and Patents Act 1988 it is no longer an infringement in copyright to copy an article made in accordance with someone else's design and the new unregistered design right is also confined to "articles", although no specific definition of this term is included in the statute in connection with the unregistered design right. Thus, it appears that parts of the type excluded from registered design protection in the present case are not protectible in any way, except perhaps by way of a common law action for passing off if they are sufficiently distinctive as to have acquired some secondary meaning.