The second Kate got backstage, she says she called her kids—but didn't get quite the reaction she expected from her 8-year-old daughter, Mia.
"I said, 'Hi, Mia, did you jump up and down?'" she says. "[Mia] says: 'Yes, I did, Mum, I did. I need to talk to you about the dress—it was gray.' She was absolutely mortified I wore a gray dress."
Kate says she doesn't consider herself a fashionista or follow the latest trends. But one thing she says she did know is that she didn't want a lot of dresses being sent to her. "I think in this time in the economy, it's just not nice to have people make lots of dresses and you just wear one out of a possible five," she says. "So Yves St. Laurent very kindly said, 'We'd like to make something for you,' and that was what we did."