Kate Middleton and Duchess Sophie Share One Thing in Common Unlike "Royal Brides Before Them," Royal Expert Says

Kate Middleton has found a close royal confidante in the form of Prince Edward's wife, Sophie, and aside from both marrying into the Royal Family from non-aristocractic backgrounds, the pair also have one major thing in common.

"They have a sisterly bond and Sophie is like the older sister Kate never had," royal author and commentator Ingrid Seward told Hello! of the royal duo. Sophie, the Duchess of Edinburgh, married Prince Edward in 1999 and shares two children, Lady Louise and James, the Earl of Wessex, with the Duke of Edinburgh.

Like the Prince and Princess of Wales, the Duke and Duchess of Edinburgh also dated for years before getting engaged. Seward notes that this likely gave both women a strong foundation when entering the Royal Family, unlike prior royal wives such as Princess Diana or Sarah Ferguson.

"They both had really long romances with their husbands-to-be and Sophie lived at the palace," Seward said, adding, "By the time they got married, they had more knowledge than the royal brides before them about what they were getting into."

"They have a huge amount in common having probably formed a bond very much at the beginning," the author said. "Sophie was there for Kate in an unofficial capacity because she had the same experience of being a commoner marrying into the family."

Middleton married Prince William in 2011, and has since gone on to raise Prince George, 11, Princess Charlotte, 9, and Prince Louis with the Prince of Wales. The Waleses are said to be particularly close with Sophie, Edward and their children.

"They are both incredibly kind girls and have a caring side to them," Seward said of Sophie and Kate. "They are both protective of their children."

Author Robert Hardman told Hello! that although Sophie is 59 to Kate's 42, she's "not that far ahead in her motherhood journey—her son is still at school. And the two families now live close to one another."

The Princess of Wales has been recovering from a battle with cancer this year, and Seward added that "Sophie also has experience of a life-threatening illness—she nearly died when her daughter Louise was born."

Speaking about the supportive gesture the Duchess of Edinburgh gave the princess—who made a rare public appearance on Remembrance Sunday—on Nov. 10, Seward said, "The royals have always shown a human side but there is more warmth now."

Duchess Sophie placed a comforting hand on the princess's back, with Seward noting that this kind of affection is a sign of a more down-to-earth monarchu. "That gesture of Sophie putting her arm around Kate is something you wouldn't have seen a few years ago," she noted.