Listening to the 1969 compilation album "Pious Bird of Good Omen" which consisted of four singles A & B sides, two previously released album tracks, two Eddie Boyd tracks with FM backing, This was the B side to Albatross.
Kirwan was a big Django Reinhardt fan, but this was originally a piece by the jazz outfit Joe Venuti and the Eddie Lang Blue Five. Kirwan based his guitar piece on that and lifted chunks of the clarinet solo and played them over Fleetwood/McVie's interpretation of the original rhythm. Green was supposed to play on it as well, but in the end he left it all to Kirwan. Danny Kirwan was a clever kid.