After Prince William brought his and Kate Middleton 's two eldest children to Taylor Swift 's Eras Tour concert in London on Friday, royal expert Katie Nicholl is giving ET rare insight into the Prince of Wales' friendship with the "Karma" crooner. Talking with ET on Wednesday, Nicholl shares that while a source recently said Princess Charlotte is the biggest Swiftie in the family, she may have competition for that title with her father -- who has a history with the 14-time GRAMMY Award winner. "I'm not sure that Princess Charlotte is the biggest Swiftie of the family or whether it's actually Prince William.
I know he loves her music," Nicholl says, adding of 34-year-old Swift and 42-year-old William, "They have a great connection, they're good friends." So if Princess Charlotte really is looking to give her father a run for his money, she has several years of fandom, one hilarious video of herself "shaking it off" and an on-stage experience with the hitmaker to make up. In 2013, the Prince of Wales and Swift sang alongside Jon Bon Jovi at the Centrepoint Gala Dinner at Kensington Palace in London, belting out "Livin' on a Prayer.
" Photos and videos from the night show the trio having a blast together while singing Bon Jovi's classic tune, and embracing after receiving a standing ovation from the crowd. Nicholl says she was in attendance that night and that Swift and William, it was just the start of what would be a long and prosperous friendship. "They remained good friends .
