Initially formed in 1968 in Cheltenham by Johnny Coppin and Dave Bell, the band were augmented in 1971 by the addition of Al Fenn and Geoff March. Their first managers included future comedian Jasper Carrott.
Decameron released four albums: Say Hello to the Band (1973), Mammoth Special (1974), Third Light (1975), and Tomorrow's Pantomime (1976). These latter three albums have since been reissued in full on a double-CD anthology entitled Parabola Road. The first album has also been re-released on CD as a single disc with nine extra previously unreleased tracks.