The Duke and Duchess of Cambridge were among the family members to visit the Queen during her break at Balmoral this summer.
Prince George, Princess Charlotte and Prince Louis, share a close bond with their great-grandmother, and the Duchess has previously spoken about the Queen's sweet tradition for her great-grandchildren whenever they visit.
In her first solo TV interview for the 2016 ITV documentary, Our Queen at 90, Kate revealed the monarch's love for her family.
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Speaking about her daughter Charlotte's birth, the Duchess said: "The Queen was really thrilled that it was a little girl and I think as soon as we came back here to Kensington, she was one of our first visitors here. I think she's very fond of Charlotte. She's always watching what she's up to."
She added: "George is only two and a half and he calls her 'Gan-Gan'. She always leaves a little gift or something in their room when we go and stay, and that just shows her love for her family."
The Cambridges traditionally visit the Queen at her Scottish estate during the summer and spend Christmas with the monarch at Sandringham, staying at their nearby country home, Anmer Hall.
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The Queen with Prince George at Charlotte's christening in 2015
Kate enjoyed a rare invitation to Balmoral before her engagement to Prince William in 2010.
The royal girlfriend was pictured in the Highlands with her future father-in-law, the Prince of Wales, back in August 2007, months after she and William reconciled their relationship following a brief split.
Kate, William and their friends were also spotted in Scotland in 2009, and the following year, the future Duchess' parents, Carole and Michael Middleton, were invited to the Queen's estate.
The Duke and Duchess of Cambridge will no doubt be preparing for a busy autumn schedule as their children head back to school and nursery in the coming week.
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