The 62-year-old is said to be on the verge of moving to expand the commercial potential of his family's historic Althorp estate in Northamptonshire just days after the publication of his controversial Princess Diana memoir, Swan Song: Diana, My Sister.
Intellectual Property Office records cover a wide range of food, drink and retail products connected with the Spencer name, while the development comes as the Duchess of Sussex continues to build her As ever lifestyle business around fruit spreads, marmalade, honey, wine and other products.
"First Spencer imitated Prince Harry with attacks on the royal family, and now he is doing a Meghan - and appears to be planning to make jam," a source told The Sun.
Markle's As ever business sells jams and honey, alongside tea, wine, candles and other lifestyle products.
Spencer's apparent proposed venture would have an unmistakably personal backdrop.
Althorp has been the Spencer family estate for centuries and is also where Princess Diana was laid to rest following her death aged 36 after a car crash in Paris in 1997.
Spencer is going through a turbulent time following the publication of his Swan Song memoir, which has generated a bitter public dispute over his account of Diana's life and death.
Spencer has made a swathe of damaging allegations about King Charles, including claiming the then-Prince of Wales sounded "giddily elated" following Diana's death and later told him: "Rest assured, we'll forget her soon enough".
Buckingham Palace took the unusual step of publicly challenging his account.
"While we do not comment on books as a matter of principle, His Majesty is mindful that the pain of fraternal grief can cloud reason, affect judgment and colour memory in ways others do not recognise, even many years after such a loss," a palace statement said.
Spencer stood by his recollection and said he did not write the book as an attack on the King.
Diana's former butler Paul Burrell has challenged Spencer's portrayal of his relationship with his sister during the final years of her life.
"They barely spoke. He was not part of her world," Burrell said on Piers Morgan Uncensored, about the siblings' relationship before Diana's death.
"I'd think (Diana's) last five years … are pretty vague in the book because (Charles) knows nothing about them," Burrell told The Sun:
He also quoted Diana as saying: "My family only want me when they want the best seats in the best restaurants or want to sit in the Royal Box at Wimbledon".
Spencer has said the approaching 30th anniversary of Diana's death prompted him to record his memories in his memoir from his perspective.
