Sir Laurens van der Post, 90, an author who was considered the spiritual guru of Britain’s Prince Charles. A native of South Africa who always said he lived with “one foot in Africa and one in England,” Van der Post was the godfather of Charles and Diana’s older son, Prince William, now 14. Van der Post was also a trusted confidant of Margaret Thatcher, a former neighbor of his in Chelsea, England. He traveled frequently with Prince Charles and shared the prince’s interest in conservation. Van der Post particularly sought to preserve the Kalahari Desert and protect it from tourism. He served in the British army during World War II and was imprisoned by the Japanese. He later served as an officer on the staff of Lord Mountbatten, one of Charles’ favorite relatives. Van der Post’s books were mostly about Africa and included “In a Province,” “The Dark Eye in Africa” and “The Lost World of the Kalahari.” Several of his books were made into movies, such as “A Far Off Place” and “The Seed and the Sower,” which was retitled “Merry Christmas, Mr. Lawrence.” On Sunday in London.