Fleetwood Mac is a band with many faces. In contrast to their poppy sound of the 70's, Fleetwood Mac actually started out in the 60's as a psychedelic blues band under guitarist Peter Green's lead. Pious Bird of Good Omen was originally released in 1969 as a compilation of the band's bluesy roots: their first four UK singles and their B-sides and two tracks by bluesman Eddie Boyd with Fleetwood Mac backing.