CIPRG1135 - Glossary: Design Right
You should check the other guidance available on GOV.UK from HMRC as Brexit updates to those pages are being prioritised before manuals.
Rights in designs allow businesses to prevent others from copying a design or drawings of the design and significant parts of the design. In the broadest sense design rights are the copyright of manufacturing industries. Greater protection can be had by registering the design but ownership of the design extends from its inception and both registered and unregistered rights may exist concurrently. A breach of a design is also often referred to as Piracy.