Boléro

"Boléro" was a piece of music. Ian Chesterton once noted that the people of the year 64 would not have heard it. (PROSE: Byzantium!)

Tobias Zed was listening to it whilst working on the ancient inscriptions found on Krop Tor. The music stopped playing when the Beast contacted Toby through his mind. (TV: The Impossible Planet)

When the BBC World Service played "Boléro" on the radio in 1953, Sylvia O'Donnell remarked in disgust that they would still be playing a series of "light classics" for mutated cockroaches even if the world went up in nuclear flame. (AUDIO: A Thousand Tiny Wings)

Behind the scenes
The non-narrative source Doctor Who: The Encyclopedia states that, as in real life, Maurice Ravel composed the song in 1928.