The Duchess of Cambridge had a tour around the "Downtown Abbey" set in March, where she had a chance to meet the casts of the hit TV series. Despite being pregnant with Princess Charlotte, Kate Middleton reportedly had so much fun on the set that she overstayed her visit.

Jim Carter, who plays Mr. Carson in the hit ITV drama, told E! News' Marc Malkin that Kate may have lost track of time during her visit, because she is such a big fan of the show.

"I don't think she'd been on a film set before or a TV set so she was intrigued by how different it looked on the screen and in reality. She overstayed. She stayed long. She was having such a good time," he said.

Meanwhile Laura Carmichael, who plays Lady Edith in "Downtown Abbey," also expressed her pleasure in meeting the Duchess of Cambridge. She told Malkin that they didn't really know what to expect of Kate's visit and recalled that they "all got quite shy" because they were star struck. However, Kate reportedly led the conversation.

When asked what they talked about, Carmichael said she talked to Kate about catering, while Lesley Nicol, who plays Mrs. Patmore, said she talked to the Duchess of Cambridge about chocolate.

"It was lovely. She's so normal. I know everyone says that but she really does try to make everyone feel at ease," Carmichael told Malkin during the BAFTA-LA's pre-Emmys Tea Party at the SLS Hotel on Saturday.

"Downtown Abbey" creator Julian Fellowes also had nice things to say about Kate's visit, calling it a "seal of approval." He also described the duchess as "very charming." Fellowes said that since Kate is such a huge fan of the show, she was able to talk to the cast and crew properly.

"It was a great thrill and treat. We were very honored," Fellowes said.

Photos of the Duchess of Cambridge's visit to the set have been shared by Variety. According to the site, 4-year-old twins Zac and Oliver Barker, who play Lady Mary's son George, greeted Kate when she arrived on the set in the morning.

The Duchess of Cambridge also visited the hair and makeup department and had a chat with the other cast members including Phyllis Logan, who plays Mrs. Hughes and Michelle Dockery, who plays Lady Mary Crawley.