It's thought that the Queen, 93, and Kate, 37, have bonded over the way they both balance family life with their royal duties.
This was particularly evident during the Remembrance Sunday service at the Cenotaph in London.
Kate and the Queen stood together on the same balcony throughout the ceremony, and could be seen talking quietly together at various points during proceedings.
When Big Ben chimed at 11a.m., the country observed two minutes of silence to remember those fallen in the line of duty.
Down below, all the Queen’s children, along with her grandsons, the Dukes of Cambridge and Sussex, and her cousin, the Duke of Kent, stood smartly to attention in their uniforms.
Royal biographer Claudia Joseph also spoke kindly of the Duchess, and told the publication this year had been "Kate's year".
She revealed: "She’s very much the girl next door, from how she dresses to how she behaves and interacts with people on engagements.
"She is likeable and relatable and that has made her very popular."