Kate Middleton was cognizant of the prominent role she played during President Donald Trump's state visit to the U.K.
Speaking exclusively to PEOPLE about the Princess of Wales' impact during the trip, which ran from Sept. 17 to Sept. 18, royal biographer Ingrid Seward says that the future queen was "very aware" of the spotlight on her.
Princess Kate, 43, has gradually resumed duties after undergoing treatment for cancer in 2024 (she shared in January that she is in remission), and Seward says that she was "animated and happy and having a laugh" at the state banquet.
"She lightened the whole evening. She lit up the table with the megawatt smile. There was a lot of pressure on her because all eyes were on her," says the editor-in-chief of Majesty magazine. "She would be very aware that the most important person there was the King, but she can't help that all eyes are on her."
"She never looked as good as she did the other night. She looked magnificent. She looked golden, and it's definitely the best I've ever seen her look at a state banquet," Seward adds about Kate's princess moment in a golden Phillipa Lepley evening coat with gown.
As they have for other state visits since King Charles' accession to throne in 2022, Princess Kate and Prince William played a major role in helping to host the U.S. president and his wife, first lady Melania Trump.
The Prince and Princess of Wales were the first members of the royal family to welcome the Trumps in Windsor on Sept. 17, accompanied them to meet the King and Queen Camilla, attended the lunch at Windsor Castle and state banquet that night, where Kate sat next to the president.
"She obviously amused him," Seward says about the photo of Princess Kate giggling alongside Trump. "She is just a doyenne of perfect manners. He must have made her laugh."
"She is definitely showing traits of being a remarkable future queen," Seward says, adding, "She has the most beautiful smile which captivates everyone. It's just magical."
The state visit also showed the scope of the "soft power" that the royal family has.
"It was really uplifting. It showed what we can really do when we push out the stops. Despite everything that's going on in the world, we are still the best at putting on a show of pomp and circumstance," says Seward. "Years ago, Charles said we must never lose that because that is what we do best -- and he is absolutely right."
After the King, 76, and Queen, 77, bid farewell to Trump, 79, and Melania, 55, on Sept. 18, Princess Kate stepped back into the spotlight by undertaking her first joint appearance with the American first lady.
The Princess of Wales and Melania visited a group of young children involved in the U.K's Scouts Squirrels program, connecting to Kate's role as joint president of the Scouts, an outing at which the first lady smiled throughout.
Princess Kate and Melania have both made children's causes a focus of their public work, and they seemed to be at ease in one another's company.
"She chatted to Kate quite a lot. Everybody wants to talk to Kate," the royal author says about their rapport on display that day.
As to whether the Princess of Wales is the royal family's "secret weapon," Seward says it's simple: "She is the weapon, not a secret one," emphasizes the author of several books on the late Queen Elizabeth.