The stanzas beginning, 'And did those feet' are among the most famous works written by the Romantic poet and artist, William Blake. Set to music by Hubert Parry in 1916 and renamed, 'Jerusalem', this hymn has become an emblem of Englishness in the past century, and is regularly invoked at sporting events, public and private ceremonies, and, of course, as part of Last Night of the Proms. Yet when Blake first engraved his lines in his epic work, Milton...