Longbranch Pennywhistle was a country rock/folk music group consisting of Glenn Frey and John David Souther.They played as a duo in the late sixties at Doug Weston's Troubadour Nightclub in West Hollywood, Calif. They released a self-titled album in 1969 under the Amos Records label. However, the label dissolved a couple years later in 1971, and the group split up. Shortly thereafter, Frey formed The Eagles, after meeting Don Henley at the Troubadour bar in 1971. Souther and Frey would continue to collaborate, also with fellow Eagle Don Henley, occasionally on such Eagles classics as "The Best of My Love", "New Kid in Town", "Victim of Love", "The Sad Café", and "Heartache Tonight".
They also recorded the song "I Can't Believe It" used in the 1971 film Vanishing Point. This song does not appear on Longbranch Pennywhistle's only album.