A Sunday tabloid reported that Ferguson had offered access to Andrew, Britain's special representative for trade and investment, to an undercover reporter. Her price? Allegedly a half-million pounds ($724,000), with a $40,000 down payment..
The front page read "Fergie 'sells' Andy for 500k" and the story splashed around the world. Ferguson issued a statement apologizing for causing embarrassment and a "serious lapse in judgment" and said Andrew "was not aware or involved in any of the discussions that occurred."
Ferguson, 50, was once considered a lively spark, just the thing to brighten up Britain's staid royal family -- a role she felt unable to fulfill.
"I was never cut out for the job, and the harder I pushed, the more things fell apart," she wrote in her 1996 memoir, "My Story."
"Even at my dizzy height of popularity, I knew that the clock would strike 12 and I'd be seen for what I was: unworthy, unattractive, unaccomplished. And finally, logically, undone."
Her career in some respects ran parallel to that of Diana, Princess of Wales. It was Diana who invited Ferguson to be Andrew's date at Royal Ascot, leading to a marriage in 1986.
The couple separated in 1992, the same year as Prince Charles and Diana. Ferguson and Prince Andrew divorced, amicably, in 1996, the same year that Charles and Diana parted on less friendly terms. Both women were stripped of the "royal highness" aspect of their titles, but both stayed in the public spotlight.
The big difference was that Charles settled a fortune on his ex-wife, while Ferguson complained to the News of the World that she got just 15,000 pounds ($22,000) a year because it was based on the income Prince Andrew earned when he was a naval officer.
Even before her split with Andrew, Ferguson made headlines -- and they weren't positive. There were reports of a romantic link in 1989 with a Texas oil tycoon. Then, in 1992, intimate photographs of Ferguson and John Bryan, an American businessman were published by the Daily Mirror. As the BBC dryly observes on its website, some of the photographs "appear to show Mr. Bryan kissing the duchess' foot." And she wasn't wearing a top.
To make it worse, Ferguson was staying with the royal family at the their summer base, Balmoral Castle in Scotland, when the pictures were published.
"It would be accurate to report that the porridge was getting cold," she wrote in her memoir, ghostwritten by American sports writer Jeff Coplon. "Eyes wide and mouths ajar, the adults were flipping through the Daily Mirror and the rest of the tabloids -- until they saw Andrew and stopped, as it never feels quite right to be gazing at your brother's wife when she hasn't all her clothes on."
"I was a royal duchess, and I had shown affection to a man not my husband, and had been found out -- end of story. No matter that Andrew and I were separated. I had been exposed for what I truly was. Worthless. Unfit. A national disgrace."
But tough? No kidding. On Sunday, her day of excruciating embarrassment, Ferguson smiled and waved as she collected an award from Variety International in Los Angeles for her work with underprivileged children.
She works with several charities, and has been admired for confronting her own money troubles -- and after Sunday's report, she admitted she's in difficulty again.
"It is true that my financial situation is under stress," the statement said. "However, that is no excuse for a serious lapse in judgment and I am very sorry that this has happened."
Recently the company set up to manage her U.S. career in publishing, public speaking and media work, Hartmoor LLC, collapsed with debts of around $1 million. And according to reports in Britain, Ferguson is facing legal action over unpaid bills.
Former Daily Mirror royal reporter James Whitaker said Ferguson had worked to pay off a multimillion pound debt "by hard work and determination." She wrote books, produced films, and worked as a spokeswoman for Weight Watchers.
"But eventually these sources of income dried up, leaving her with far too little money," Whitaker wrote in the Guardian.
"People assumed she was still a big earner but they were wrong." Christopher Wilson, a royal commentator who co-wrote "Fergie -- Her Secret Life," said Ferguson has had a "roller coaster of a life, where she's had huge successes and these pratfalls."
"She's a fighter," he said. "At the moment it looks like she really is reaching the end of the road, but it wouldn't surprise me to see her bounce back."