Princess Diana reportedly called Prince Charles “sir” before they tied the knot. And it has now been revealed that another person was forced to do the same.

In the book “My Story,” Sarah Ferguson revealed that royal protocol dictated that she calls Prince Andrew “sir” when they first met up until their wedding day.

The Duchess of York and Prince Andrew first crossed paths at Windsor Castle in 1985 and the mom of two couldn’t contain her excitement upon seeing how handsome the latter was.

“When I turned to face Andrew, I was struck by how handsome he was in his morning suit, and soon my worries had flown. Andrew was easy, and I felt relaxed with him, for me a rare condition – even though I addressed him as ‘Sir,’ as per protocol,” she said.

In the book, Ferguson revealed that she and Prince Andrew had a lot of things in common. They liked the same jokes and they also loved good pranks. During one occasion, the couple’s unique sense of humor was put on display.

“When the chocolate profiteroles came around, I tried to pass – I was on a diet, as usual – but Andrew claimed that refusing them would be improper etiquette. Then when it was his turn to take his portion, he refused – ‘No, thank you very much!’ – and I indignantly swatted him on the shoulder with the back of my hand,” Fergie recounted.

The royal couple’s marriage was described as a “thunderbolt.” Unfortunately, it didn’t last. Ferguson revealed that she struggled with her life as a royal especially since Prince Andrew wasn’t always around. After tying the knot in 1986, the couple decided to call it quits in 1996. Their separation was first announced in 1992, and their divorce was finalized four years later.

Prince Andrew and Ferguson were blessed with two children together, Princess Beatrice and Princess Eugenie. Until today, the couple has stayed as friends.

Prince Andrew, Sarah Ferguson
Pictured: Prince Andrew, Ferguson attend the Virgin London Marathon on April 25, 2010 in London, England. on April 25, 2010 in London, England. Getty Images/Gareth Cattermole