Before they called each other husband and wife, Prince William and Kate Middleton reportedly had several code names for each other.

According to excerpts from a new book, "Catherine, The Princess of Wales," obtained by People magazine, the royal would "often whisk Catherine off to Highgrove or Sandringham or to a cottage on the Balmoral estate," in the early 2000s, when they were both students at the University of St. Andrews.

"Occasionally, they checked into hotels, using the names Mr. and Mrs. Smith, which doubtless fooled no one," British author Robert Jobson wrote.

PRINCE WILLIAM AND KATE MIDDLETON, KATY PERRY AND ORLANDO BLOOM: COUPLES WHO MAY INSPIRE YOU TO TEXT YOUR EX

Prince William in a black hat and jacket with a red shirt laughs at a match with Kate Middleton in black

When they lived together and with their friends as roommates in college, Prince William and Kate Middleton would go on private getaways.  (Richard Heathcote/Getty Images)

The popular action-comedy film of the same name starred Brad Pitt and Angelina Jolie as John and Jane Smith, a husband and wife who worked for opposing assassin agencies.

Brad Pitt in a suit holds Angelina Jolie by the leg in a steamy scene from "Mr. and Mrs. Smith"

Brad Pitt and Angelina Jolie starred in the 2005 film "Mr. and Mrs. Smith." (Maximum Film/Alamy Stock Photo)

LIKE WHAT YOU’RE READING? CLICK HERE FOR MORE ENTERTAINMENT NEWS

"Mr. And Mrs. Smith" was released in 2005, the same year the Prince and Princess of Wales graduated from school, making it unlikely the film was the inspiration for the code names.

But "Mr. Smith" wasn't William's only alternate identity. In "a rather pathetic attempt to stay under the radar," the royal used "Steve" as a cover when he first started college in an attempt to be more normal. Kate reporedly helped, calling him by the fake name.

CLICK HERE TO SIGN UP FOR THE ENTERTAINMENT NEWSLETTER

Prince William in a brown suit smiles and looks down at wife Kate Middleton in a blue blazer and white shirt

According to a new book from British journalist Robert Jobson, the Prince and Princess of Wales once called each other "Mr. and Mrs. Smith." (Chris Jackson/Getty Images)

According to People, in Andrew Morton's 2011 biography, "William and Catherine," the duo used the names "Martin and Rose Middleton" to disguise themselves on vacation in the Seychelles. The trip overlapped with when the couple reunited after a brief time apart.

Prince William in a blue blazer and purple tie smiles next to wife Kate Middleton, also in blue

Prince William and Kate Middleton reportedly broke up in 2007. (Chris Jackson/Getty Images for St James's Palace)

In 2010, the lovebirds were engaged. In an interview with ITV after the announcement, William confirmed they had previously broken up, but he gave a different timeline. 

"We did split up for a bit. But that was just — we were both very young, it was at university. … We were both sort of finding ourselves and such and being different characters and stuff. It was very much trying to find our own way, and we were growing up. … It was a bit of space."

"At the time, I wasn’t very happy about it, but actually, it made me a stronger person," Middleton added.

Prince William in a blue sweater looks down at wife Kate Middleton in blue as she speaks

The couple married in 2011. (Samir Hussein/WireImage/Getty Images)

CLICK HERE TO GET THE FOX NEWS APP

A representative for Kensington Palace did not immediately return Fox News Digital's request for comment.