The title alludes to the BBC World Service's station identification: "This is London calling ...", which was used during World War II, often in broadcasts to occupied countries.
The line "London is drowning / And I live by the river" comes from concerns that if the River Thames flooded, most of central London would drown, something that led to the construction of the Thames Barrier.
The song fades out with a Morse code signal spelling S-O-S, reiterating the earlier urgent sense of emergency, and further alluding to drowning in the river.
"London Calling" was recorded at Wessex Studios located in a former church hall in Highbury in North London.
In 2004, Rolling Stone rated the song as No. 15 in its list of the 500 Greatest Songs of All Time.