What could be more Shakespearean than a ghost?

In the final series of the Netflix programme The Crown, Princess Diana will appear as a ghost. We are told that her apparitions will be ‘thoughtful and sensitive’ – which is rather disappointing for anyone hoping for her to have a recurring role, like Marty Hopkirk in Randall and Hopkirk (Deceased), perhaps wearing that white dress she wore to the British Fashion Awards.