One of the new Paul McCartney songs featured on his latest reissue of Egypt Station has actually been around for decades. The track, called "Frank Sinatra's Party," references Sammy Davis, Jr., Peter Lawford, Angie Dickinson, and Dean Martin, and has just been released as part of the new limited "deluxe" and "explorer" editions of the album.

The song, as any die-hard "Macca fan" will tell you, features the backing track from McCartney's summer 1976 demo, "Fishy Matters Underwater," which was previewed back in 1995 as part of the former-Beatle's syndicated radio series, Oobu-Joobu. The musical improvisation is among the string of experimental tracks McCartney laid down in his makeshift barn studio on his Scottish farm -- dubbed Rude Studios -- over his summer vactions in 1976, '77, and '78.

In the 2000 documentary Wingspan, McCartney was interviewed by daughter Mary, and shed light on the purpose of Rude Studios: "Up at the farm, I'd had a little four-track studio put in there. So, I was able to demo and experiment and make bits and pieces of music."

McCartney recalled he and wife Linda hitting Rude to develop new material for Wings: "We'd make sure everybody was fed, happy, and asleep, tuck ya into bed, then we'd come out here and do bit of jamming, bit of playing, sometimes a bit of writing."

AUDIO: PAUL MCCARTNEY ON RUDE STUDIOS
AUDIO: PAUL MCCARTNEY ON RECORDING ON SCOTTISH FARM