Queen Elizabeth II, who passed away in September 2022, reportedly left a sealed death-bed letter for her son and heir, King Charles III. Biographer Robert Hardman reveals this in his new book about the immediate aftermath of the Queen's passing. The Queen had been working on her official correspondence until the end, and her final red box contained a private letter for the new King. The contents of the letter remain unknown, but it is believed to contain final instructions or farewells.