1971 is regarded as one of the more unusual years in British pop music, with previously underground rock bands puncturing the mainstream bubble via a mixed-up sound now referred to as "progressive pop". This expansive three-disc set tells the story of this curious moment in time, offering up a mixture of notable chart hits (see cuts by the Kinks, Curved Air and Atomic Rooster, for starters), high-quality but lesser-known album tracks (Procol Harum, ELP, Cressida, Help Yourself, Legend), and material previously confined to classic (but sometimes overlooked) "45s" (Kevin Ayers, Medicine Head, The Move). With 71 tracks stretched across three discs it's an epic collection, but one packed full of unusual and inspired songs.