In a Rolling Stone interview, Crosby remarked: "That is a very unusual song, it's in a very strange tuning (EBDGAD) with strange time signatures. It's about three women that I loved. One of whom was Christine Hinton - the girl who got killed who was my girlfriend - and one of whom was Joni Mitchell, and the other one is somebody that I can't tell. It might be my best song." According to Robert Christgau, the song was based on a three-note motif from the 1960 Miles Davis album Sketches of Spain. The album CSN (box set) contains a demo version of the song played by Crosby on guitar, Jack Casady of Jefferson Airplane on bass, and Cyrus Faryar of Modern Folk Quartet on bouzouki. In the liner notes, Crosby says of the song: "When all my friends were listening to Elvis and 1950s rock 'n' roll, I was listening to Chet Baker, Gerry Mulligan and West Coast jazz. Later I got involved with the folk music scene. After getting kicked out of the Byrds I didn't have a plan, but I went back to my roots, and "Guinnevere" is a combination of these two influences." The song also deals with the importance of freedom. It may have been written about Queen Guinevere from the perspective of a man addressing a woman; it has been speculated that Crosby wrote about her from the perspective of Sir Lancelot of ancient Welsh lore. "Guinnevere" could also be referring to Nancy Ross, who lived with David Crosby and (according to author David McGowan) drew pentagrams on the wall. She would leave Crosby in 1966 for Gram Parsons, the grandson of a citrus fruit magnate. These facts correlate to the "Nancy Ross" theory: in the song, Crosby sings that Guinnevere "drew pentagrams," and that "peacocks wandered aimlessly underneath an orange tree. From: https://en.wikipedia.org/wiki/Guinnevere
