Forty years ago, Elton John's "Philadelphia Freedom" burned up the pop and R&B charts stateside. Now the story of what lies behind the songman's hit has been revealed—along with additional insight about John's longtime friendship with Billie Jean King. It begins at a party, and it's a tale told at, of all places, EltonJohn.com.

John wrote "Philadelphia Freedom" for King. Any tennis fan worth his Twitter bluster knows that by now. Among the most interesting morsels about the song's creation, this: John told King ahead of time that he was penning a track in tribute to her. The World Team Tennis squad she fronted in Philly was an inspiration, as John followed the team's movements with aplomb, delighted by the sport and by his winsome friend.

What's more, for all you metered-poetry mavens out there, John reportedly loves the song's title because "Philadelphia" itself is iambic. As for King herself? She loves that this treasured ditty has nothing to do with tennis, as John purely intended it, and she relishes the titular word itself: "freedom."

These days, King and John bring celebrated tennis stars into the fold of their annual Smash Hits charity fundraiser. The bombast from each comes through more subtly than it did in the 1970's, to be sure, but their respective legacies have been solidified for all of time. They speak more softly even as they wield bigger sticks. After all, from the day they were born, they've waved the flag.

Got a tip or a point to make? Hit me on Twitter at @jonscott9.