Jackie Kennedy was unimpressed by Buckingham Palace until Queen Elizabeth's advice changed everything: author

Queen Elizabeth II gave Jackie Kennedy a piece of advice that helped ease any awkwardness between the two iconic women.

The claim was made by Caroline Hallemann, author of "The Kennedys & the Windsors," which explores the two dynasties and how their paths crossed over the years. Hallemann noted that although the two women were hardly kindred spirits when they met, the monarch's words left a lasting mark on the first lady.

"There's a great quote that Queen Elizabeth allegedly said to Jackie during their 1961 meeting at Buckingham Palace," Hallemann told Fox News Digital. "Jackie had been talking about how she struggled a bit on a recent visit to Canada being in the public eye, being in the spotlight all the time."

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"The queen said, 'You learn to save yourself,'" said Hallemann. "And I think that interaction between them is quite telling because, at that moment, Jackie was still a new first lady. She was shining brightly and was making such an impact on the global stage. By contrast, Queen Elizabeth had not only been queen for several years but had known for many years that it would eventually be her future."

"And so, you learn to save yourself — this is for the long haul," Hallemann continued. "You can’t expend all that energy at once because you have to manage it. And I think that helps illustrate how the royals have managed fame."

According to Hallemann, the first lady accompanied her husband, President John F. Kennedy, to Buckingham Palace in June 1961. The visit was part of an overseas trip during which she spent time with her sister, Lee Radziwill, who lived in London with her husband, Prince Stanisław Albrecht Radziwiłł of Poland, and their infant daughter.

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While Kennedy was excited to meet the royals, she was reportedly disappointed that the palace wasn't as grand as she had hoped. In the book, Kennedy was reportedly "unimpressed by the drafty, aging building."

"You could almost imagine the wheels turning in her mind of how she would restore the White House, so that it wouldn’t disappoint visitors the way the palace had disappointed her," Hallemann wrote.

Kennedy’s friend, photographer and legendary gossip Cecil Beaton, wrote in his diaries that the first lady found the royals "tremendously kind and nice." However, "she was not impressed by the flowers, or the furnishings of the apartments at Buckingham Palace or by the queen’s dark blue tulle dress and shoulder straps, or her flat hairstyle."

Royal commentator Meredith Constant told Fox News Digital she was not surprised by the reported account.

"Like most Americans, Jackie had a much grander idea of the British monarchy in her head than the reality that was presented to her," said Constant.

"Interestingly, Jackie was at the D.C. welcome for then-Princess Elizabeth and Prince Philip in 1951. Jackie was an inquiring camera girl for the Washington Times-Herald. One of the questions she reportedly asked photographers was if Princess Elizabeth was as pretty as her picture. You have to imagine she had Elizabeth and her life built up in her mind that the reality was somewhat deflating."

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There could have been another reason Kennedy was initially unimpressed. Hallemann wrote that initially, the Radziwills were excluded from the intimate visit as the couple had both been previously divorced.

"As the head of the Church of England, which frowned upon divorce and remarriage, the queen saw it as inappropriate to host the couple," Hallemann wrote. However, "eventually, after some back and forth, the queen relented."

Hallemann also wrote that Kennedy "couldn’t completely hide her disappointment with the selection of attendees present." While she was hoping to meet Princess Margaret and Princess Marina of Kent, whom the president had met when he lived in London before the war, the women weren’t in attendance.

"No Margaret, no Marina, no one except every Commonwealth minister of agriculture they could find," Kennedy reportedly told writer and "pseudo-stepbrother" Gore Vidal.

And Kennedy may have "silently and smilingly stolen the show," the book noted.

While the queen wore a voluminous gown paired with sapphires and diamonds, Kennedy wore a sleek ensemble. Her look was described as "modern and elegant," helping cement Kennedy's status as a style icon in the U.K.

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"The difference between the 'Queen of Fashion' and the Queen of England was that Jackie was brought up in a world of designers flocking to dress her," royal broadcaster Ian Pelham Turner told Fox News Digital.

"The Queen of England wore simpler attire to reflect the period after the Second World War, when the country was still coming to terms with the cost. The queen did not want to be flamboyant. Instead, she wanted to connect with people. Elizabeth also followed the trend of army wives. Her shorter hairstyle was seen as functional by officers’ wives of the period."

Hallemann wrote that Kennedy allegedly told Vidal that while she found Prince Philip "nice but nervous," the queen was "pretty heavy-going" in being reserved and polite. When Vidal later told Princess Margaret this account, the royal retorted, "But that’s what she’s there for."

But there was one thing the women would bond over.

"Both ladies warmed to each other and bonded over their love of horses," British broadcaster and photographer Helena Chard told Fox News Digital.

Royal expert Richard Fitzwilliams agreed.

"[You have to remember], the queen and the first lady inhabited very different worlds," he said. "The Kennedys had an iconic glamour that was unique. But the queen represented an institution going back over 1,000 years. They had little in common."

But relations softened between the women due to time and tragedy. It's believed that the queen's advice on navigating fame stayed with Kennedy during the toughest moment of her life.

"Queen Elizabeth II is known to have admired Jackie’s resilience following the assassination of the president in 1963," British royal expert Hilary Fordwich told Fox News Digital. "She survived such a trauma, which would have destroyed most, with a public dignity, composure and class unmatched to this day."

"If there had been any sort of real or deep animosity, it is highly unlikely the queen would have gifted an acre of meadowland at Runnymede, legally ceded to the U.S. This was in May 1965, with Jackie and her two children standing beside the queen at the dedication."

In the book, Hallemann wrote that the queen was "shocked and horrified" by the president’s assassination and immediately reached out to the devastated first lady. She also wanted to attend Kennedy’s funeral, "but given that she was expecting, that wasn’t an option." Philip attended instead.

"The morning after [John F.] Kennedy's death, the tenor bell at Westminster Abbey tolled every minute between 11 a.m. and noon in the president's honor, and she ordered the royal court to observe a full week of mourning — a rare distinction for someone outside the royal family, and an American, no less," Hallemann wrote.

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During one private moment, Kennedy saw Philip playing with her son. "I’ve got one like that," he told the nanny.

Constant said that over time, the women developed a deep appreciation for one another.

"Both women discovered shared interests, but one of the biggest was projecting a particular image of their family," she said. "With President Kennedy’s assassination, Jackie became the queen of her own realm, thinking not just about the future, but how to preserve the past and the Kennedy legacy. It was a responsibility that both women took incredibly seriously."

"I think the queen grew to respect Jackie, and Jackie respected what the monarchy, or the illusion of monarchy, represented through her Camelot after Jack’s death," she added.