The last two minutes of the song mark the first appearance of a guitar solo by Gilmour on a Pink Floyd album, though it has been disputed to be former guitarist Syd Barrett by Andrew King, their manager at the time.

The song shares the theme of benevolent extraterrestrial intervention in human affairs with the 1951 film The Day the Earth Stood Still and Arthur C. Clarke's 1953 novel Childhood's End.

Along with "Set the Controls for the Heart of the Sun" and 1969's "Cirrus Minor", it is one of only three Waters-penned lyrics to feature science fiction themes prior to his 1992 solo album Amused to Death.

The first verse relates the realisation of an apparent prophecy that "something will be done" when a "mighty ship / Descending on a point of flame / Made contact with the human race at Mildenhall".

Carter's father, seeing the spacecraft, "knew the Rull revealed to him / The living soul of Hereward the Wake", a phrase which appears to reference both science fiction writer A. E. van Vogt's 1948 short story "The Rull" (which tells of psychological battle of wits between a human and a hostile alien with hypnotic powers) and a legendary 11th century leader of resistance to the Norman invasion of England who is believed to have roamed The Fens of Cambridgeshire.