The lyric asks, “And did those feet in ancient time walk upon England’s mountains green?” The canonical answer is “green.”
The words come from William Blake’s 1804 preface poem to *Milton*, commonly known as “And did those feet in ancient time.” Blake imagines whether a divine presence once walked in England, then contrasts that ideal with “dark Satanic Mills,” usually interpreted as a critique of industrialization and spiritual or social oppression.
The poem became widely known as the hymn “Jerusalem” after Sir Hubert Parry set it to music in 1916, during the First World War. Parry’s arrangement, later adapted by Edward Elgar, helped turn Blake’s text into a major English patriotic and ceremonial song.
A common mix-up is answering “pleasant,” because that word appears in the next line: “And was the Holy Lamb of God / On England’s pleasant pastures seen?” “Green” belongs specifically to “mountains.”