But together, the sisters-in-law were the 1980s tabloid darlings, and carried out headline-making behaviour from the early days of their respective relationships.
This reached a crescendo on Fergie’s hen’s night, when the pair apparently attempted to play a series of tricks on palace officials and Prince Andrew himself.
“There was always trouble afoot when the two women got together,” royal insider Sarah Bradford told Daily Mail.
“On Fergie’s hen night she and Diana wore grey wigs, dressed up as policewomen and pretended to arrest a ‘prostitute’ outside Buckingham Palace.”
Ms Bradford went on to claim the pair were promptly put in a police van by royal security officers, before one of the men recognised Princess Diana.
But that wasn’t the end of the duo’s night of laughs and after visiting London’s most well-heeled nightclub, Annabel’s, they returned to the palace and took the antics to the next level.
“But they then succeeded in tricking the policemen on the gates at Buckingham Palace and they shut the gates in Andrew’s face as his car approached.
“Fearing an ambush he screeched into reverse....That’s when Fergie wondered if she’d gone too far.”
However, all apparently turned out well enough for Prince Andrew and Fergie’s wedding to go ahead months later in July 1986.
The couple later had two daughters, Princesses Beatrice and Eugenie but divorced in 1996 amid years of scandal and allegations of affairs.
Despite their long-divorced status, the former couple have continue to spark rumours of a reunion over recent years and even live together at the prince’s home near Windsor Castle.