The couple tried to fly under the radar in the early days of their romance, but their pseudonyms “fooled no one,” according to a new biography

Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge pose for the official tour portrait for their trip to Canada and California in the Garden's of Clarence House on June 3, 2011 in London. England

Prince William and Kate Middleton on June 3, 2011. Photo: Chris Jackson / Getty

Kate Middleton and Prince William reportedly chose interesting pseudonyms in an attempt to stay under the radar while traveling.

In his new book Catherine, the Princess of Wales, Robert Jobson details how, while students at the University of St. Andrews, Prince William used to “whisk Catherine off” for nights alone and check into hotels under an alias.

As the two fell in love in the early 2000s, they were roommates living off-campus with two other classmates. When the couple wanted to get away from it all, “he’d often whisk Catherine off to Highgrove or Sandringham or to a cottage on the Balmoral estate,” Jobson wrote in the new book, out Aug. 6. “Occasionally they checked into hotels, using the names Mr. and Mrs. Smith — which doubtless fooled no one.”

Prince William walks with his girlfriend Kate Middleton after his graduation ceremony at RAF Cranwell on April 11, 2008 in Cranwell, England

Prince William walks with his girlfriend Kate Middleton after his graduation ceremony at RAF Cranwell on April 11, 2008 in Cranwell, England. Pool/Anwar Hussein Collection/WireImage

Roughly around the same time, Angelina Jolie and Brad Pitt were starring in the 2005 hit movie Mr. and Mrs. Smith, the film set on which they met and fell in love. However, it’s unlikely that the pair used the film as inspiration — they graduated from St. Andrews in 2005, so this was likely occurring before the movie came out and, as The Mirror reports, Mr. and Mrs. Smith are very common names in the U.K.

The “Mr. Smith” moniker wasn’t the only time Prince William adopted a fake name in an attempt for more privacy. In 2001, the same year he entered university, he used the name “Steve” in “a rather pathetic attempt to stay under the radar,” Jobson wrote. Kate even played along and used the fake name, Jobson added, as the eyes of the world were upon him and Prince William simply wanted to have a relatively normal college experience.

In addition to the “Mr. and Mrs. Smith” moniker, Andrew Morton wrote in his biography of the couple, William and Catherine, that during a vacation to Seychelles later in their romance, the two chose the names “Martin and Rose Middleton” for the 2007 visit, right around the time they were reconciling after their brief split that year.

Kate Middleton and Prince William attend day 1 of the Cheltenham Horse Racing Festival on March 13, 2007 in Cheltenham, England

Kate Middleton and Prince William in March 2007, just before their brief breakup. Indigo/Getty

The couple “spent a sublime week renewing their love affair,” Morton wrote, and author Marcia Moody wrote in her book Kate that it was on this trip that “they made an agreement with each other,” she wrote. “For the next few years, they would work and enjoy their lives, knowing that at some point when the time was right, they would be husband and wife.”

Poignantly, after their April 29, 2011 wedding, the newly minted Duke and Duchess of Cambridge returned to the Seychelles for a private honeymoon for a full circle moment.