The Benny Hill Theme

Clara Oswald added a piece of music she called "The Benny Hill Theme" to a video of the Mire being defeated in a Viking village. (TV: The Girl Who Died)

Behind the scenes
Like Clara, many people often refer to the music as "The Benny Hill Theme", due to its use as the theme tune for The Benny Hill Show. In reality the piece is titled "Yakety Sax".