Princess Diana and Sarah Ferguson
Princess Diana was jealous of Sarah Ferguson because she knew how to win the hearts of the royal family. Pictured: Prince Andrew, Ferguson, Lord Linley, Prince Edward, Prince Charles, Princess Diana, Queen Elizabeth II and Queen Mother outside her London Clarence House residence on Aug. 4, 1989. Getty Images/Johnny Eggitt

Princess Diana and Sarah Ferguson had a divorce pact while they were still married to Prince Charles and Prince Andrew, respectively. But the Princess of Wales eventually bailed out of it.

In the book “The Diana Chronicles,” royal author Tina Brown said that the Princess of Wales’ decision to bail out of her divorce pact with Fergie left the latter stranded.

“The Princess realized her sister-in-law was more useful as the ‘canary down the mineshaft’, as she put it. Diana used her sister-in-law as a constant source of intelligence on Windsor tactics and saw the way that Fergie was being bested,” she said.

Princess Diana’s former media advisor, Jane Atkinson, echoed Brown’s statements. She said that Ferguson became a very useful friend to the Princess of Wales. And if not for their friendship, Princess Diana would have gone made during her separation from Prince Charles.

Brown isn’t the only royal author who talked about Princess Diana and Ferguson’s divorce pact. In the book “Fergie, Her Secret Life,” author Alan Starkie revealed that he learned about the female royals’ divorce pact from Fergie’s lover, John Bryan.

The pact made by the Duchesses revealed that they will be divorcing their respective husbands simultaneously. But only Ferguson lived up to her part of the bargain. When she agreed to divorce Prince Andrew, Princess Diana waited for some time and she learned from Fergie’s mistakes.

In the end, Princess Diana was able to receive a bigger sum of money after she gave her terms to Queen Elizabeth II. Prince Charles and Princess Diana’s divorce was finalized in 1996. Ferguson and Prince Andrew’s divorce was also finalized in the same year.

Prince Charles and Princess Diana were first to tie the knot in 1981. Four years later, the Princess of Wales introduced Ferguson to Prince Andrew. The couple immediately hit it off and they got engaged. One year later, they also got married.