Sarah Ferguson Invited Her Lover to Husband Andrew's 30th Birthday Party at Buckingham Palace—And Queen Elizabeth Weighed In

Andrew Mountbatten-Windsor and Sarah Ferguson have been divorced since 1996, but well before their relationship ended, both parties had stepped out of their marriage. In November 1989, Ferguson met American businessman Steve Wyatt while attending the British Festival in Houston, Texas. Despite being well into her pregnancy with Princess Eugenie, Sarah started an affair with Wyatt—and even invited him to the "Dance of the Decades" at Buckingham Palace.

In his book Entitled: The Rise and Fall of the House of York, author Andrew Lownie recounts how Ferguson quickly became infatuated with the American. A source who was present at the British Festival told the author, "It was obvious that Sarah was enormously attracted to him...There was clearly a chemistry between them."

Ignoring the advice of her friend and spiritual advisor Maureen Conway, who "warned against the relationship," Ferguson then met up with Wyatt the next month when he was visiting England, carrying on with the affair throughout her pregnancy.

Princess Eugenie was born on March 23, but just six weeks later, Ferguson left her baby behind and flew on Wyatt's family's private jet to Morocco for a glamorous vacation, bringing Princess Beatrice, a nanny, "two police protection officers" and a friend along, per Lownie.

After another holiday, this time in the South of France, Ferguson hosted a dinner at Buckingham Palace to help Wyatt's oil career, bringing him along to a dinner party afterward. At the event, Lownie says she engaged in what a guest called "a display of mutual fondling I have never seen before in a three-star restaurant."

The former Duchess of York even went as far as inviting Wyatt to the housewarming party she and the former Prince Andrew held at their new home, Sunninghill Park, in October 1990.

In December 1990, the affair was still going strong. That month, the Royal Family celebrated the milestone birthdays of four family members as Prince Andrew turned 30, Princess Anne turned 40, Princess Margaret turned 60 and the Queen Mother turned 90.

To mark the occasion, Queen Elizabeth invited 800 guests to the "Dance of the Decades," a ball honoring the family's four big birthdays that year. Steve Wyatt ended up making the invite list yet again, but Queen Elizabeth and Ferguson's mother, Susan Barrantes, both gave their two cents.

According to Lownie, the late Queen "asked whether Wyatt was 'quite the sort of person you should be encouraging, dear.'" Lownie added that "Susan Barrantes was more direct," telling her daughter to "Chill him."

But Ferguson couldn't be stopped. By Christmas 1991, Lownie wrote that "divorce was discussed" by Andrew and Sarah, but Queen Elizabeth "suggested they wait six months before making a decision."

Although Fergie was carrying on a years-long affair, Andrew wasn't blameless in the marriage. Per Lownie, the former duke's driver said that Andrew "had slept with 'more than a dozen women before their first anniversary.'"

In January 1991, a series of intimate photos of the then-duchess were given to the Daily Mail by a window cleaner who allegedly found them in Steve Wyatt's apartment. However, multiple royal sources questioned whether the photos were "planted" after being "stolen from Sunninghill," as Lownie noted.

The incriminating photos included Wyatt on vacation with Ferguson and a photo of young Princess Beatrice "on his knee" without clothes. The pictures marked "the final straw for the Royal Family," as Lownie wrote in his book. A family meeting was held, and three days later, Andrew and Sarah told Queen Elizabeth they'd be separating.

As for Wyatt, he went on to propose to his future ex-wife, Cate, in 1993, leaving Ferguson heartbroken. The pair kept in touch over the years, however, with the Wyatts attending Ferguson's 40th birthday party and Sarah reuniting with Steve in Texas for Mother's Day 2017.