Kate Middleton had one major regret about her Christmas outfit

It seemed like a picture-perfect Christmas for the Cambridge family!

The Duke and Duchess of Cambridge took their two oldest kids -- Prince George, 6, and Princess Charlotte, 4, -- on their first-ever Sandringham Christmas walk last week. Joining other members of the royal family such as Queen Elizabeth, Prince Charles, Prince Edward's family and the Duke of York's family, the young royals made their way to services held at Church of St. Mary Magdalene after meeting members of the public.

Kate Middleton led Charlotte through the walkabout and held her daughter's hand as she greeted royal well-wishers. One lucky fan who had the opportunity to meet the duchess later revealed details of their conversation -- and it involved fashion!

Rachel Anvil, who greeted the family in Sandringham, chatted to the mom-of-three about her outfit -- a gorgeous grey Catherine Walker coat with a faux fur lining -- when the duchess revealed she regretted her look and should have worn something else.

"Kate was talking to my daughter about clothes and how she was feeling too hot," Rachel's mom, Karen, told reporters at Metro. "She said, 'I really shouldn't have worn this.'"

Karen, who chatted with Princess Charlotte about toys, revealed that family was incredibly genuine.

"I'm there talking to Charlotte about dolls, and my daughter's talking about fashion with Kate. It wasn't fake; it was a genuine discussion," she continued. "It was about a minute, but it was tailored to my daughter, it was like speaking to a friend. They are totally different with the public [than the press]."