During an interview , Lorde explains that part of the inspiration behind the song is a photo from an old National Geographic of a baseball player in a Kansas City Royals uniform signing baseballs for a group fans. She later explained that she took the word, "royal", and used as a theme of aristocracy for the song.
Here is the photo that inspired the hit song:
The photo, of course, is of Hall of Famer George Brett. I guess we could add one more hit to his career total.