During the London Olympics closing ceremony last year (12), the British beauty joined fellow models Kate Moss and Jourdan Dunn as they strutted down a runway.
Backstage, Campbell mingled with other U.K. celebrities who were on hand to close out the summer games, including Styles, who was there to perform with his bandmates.
But in an interview with Heat magazine, Campbell confesses when she first met the young singer, she had absolutely no idea who he was.
She says, "Kate introduced me to him at the Olympics. And I said to her, 'Whose son is he? Is he one of our model friends' kids that I just missed out on?' I didn't know who he was. Kate was like, 'Stop! No! You must know him.'"
Despite the fact Campbell was unaware of Styles' celebrity, she also tells the magazine she's a big fan of Simon Cowell and his show The X Factor, where One Direction first found fame.
She adds, "I'm a big fan of Simon Cowell. Everything he touches turns to gold and he gives people who have hopes a chance to really make their dream come true. I can only watch The X Factor if I'm in the country. I know I can watch it on YouTube, but it's always a few days later and by that time someone's told you what's happened."