‘Jerusalem’ is a cover of a traditional English hymn, given a rock arrangement by ELP. The lyrics come from a poem an early-nineteenth-century poem by William Blake, a renowned English Romantic poet. The poem was originally set to music by Hubert Parry in the early twentieth century. Parry’s hymn has since become overwhelmingly popular in England and now enjoys status as an unofficial national anthem of England, though England has no official anthem, using instead the British anthem ‘God Save the Queen’. It was upon this musical adaptation that Emerson, Lake & Palmer based their musical arrangement.

ELP released ‘Jerusalem’ as a single in 1973, but the conservative establishment at the time forbade it from radio play, disapproving of arranging a hymn (and such a culturally important one) into a rock song.