Diana was "genuinely upset" Charles refused to join her at India's iconic Taj Mahal and thought the infamous Camillagate tapes were "sick", a new book claims.
A picture of a forlorn-looking Diana sitting in front of the Taj Mahal mausoleum - Mughal emperor Shah Jahan's monument of love to his favourite wife, Mumtaz Mahal - prompted rumours about the state of her marriage during a 1992 tour of India.
Charles was committed to his own separate itinerary at the time and was in New Delhi.
"The princess, who told me she was genuinely upset by her husband's refusal to join her at the Taj Mahal, had privately decided to drive home the point," Diana's former personal protection officer Ken Wharfe writes in his book, Guarding Diana: Protecting The Princess Around The World.
When a TV journalist asked about her thoughts on the monument she turned to Charles for help and he advised, "Just say it is a healing experience," and she replied to the broadcaster, "It was a fascinating experience - very healing."
Wharfe suggests the princess gave newspapers licence to interpret the remark as a comment about her marriage when, asked what she meant, she replied, "Work it out for yourself."
Wharfe also says Diana was left feeling triumphant after the Prince of Wales was criticised over the "Camillagate" tape she branded "sick" for its infamous tampon reference.
Charles and Camilla Parker Bowles' leaked late-night telephone chat gave Diana a boost as she began rebuilding her life after separating from the heir to the throne, Wharfe says.
He quotes Diana: "'Game, set and match', she said, clutching to her a copy of the Daily Mirror containing a transcript of the Camillagate tape as we talked in her sitting room at Kensington Palace.
"Later, however, she told me that she had been genuinely shocked by some of the baser comments, particular the Prince's tampon reference. 'It's just sick,' she said repeatedly."
The recording of the 1989 telephone call featured Charles allegedly telling Camilla he would like to "live inside your trousers".
When Parker Bowles, who married the prince in 2005, joked, "what are you going to turn into, a pair of knickers?", the heir to the throne later replied, "Or, God forbid, a Tampax. Just my luck."
The transcript had been published in January 1993, just more than a month after the prince and princess formally separated.
Wharfe also writes the Princess of Wales insisted on taking a vibrator, dubbed Le Gadget, on official foreign trips.
"Le Gadget was perhaps our finest wind-up and an almost constant source of laughter," Wharfe writes.
"The small vibrator, bought as a practical joke after a staff night out in Paris during Diana's official visit there the previous November, had become her lucky mascot."
Diana was killed in a car crash in Paris on August 31, 1997.
