06/15/2001 AT 11:23 AM EDT
Once again this summer, notes PEOPLE in its latest cover story, Princess Diana's brother, Charles Spencer, 37, will unlock the doors to Althorp, his family's ancestral estate and his sister's final resting place as well as the home of the $4.1 million museum Diana, a Celebration. This year's opening holds particular resonance, however, as it will take place on July 1, the day that Diana would have turned 40. The birthday is one the princess would have regarded apprehensively, suspects her brother. "I imagine she would not have been looking forward to being 40. She was always conscious of her age and appearance," he says. "But I can't see her losing that happiness and strength she had achieved." After her painful marriage to Prince Charles, he observes, "she had reached the rebirth stage and was ready to move on." For Spencer, the continued outpouring of grief from strangers toward his sister remains disconcerting. "I find it difficult when people break down in tears," he tells PEOPLE. "I resort to a very British defense mechanism and block it out."