Another Brick in the Wall

While working as the caretaker of Coal Hill School in the early 21st century, the Twelfth Doctor whistled the beginning of part 2 of "Another Brick in the Wall". (TV: The Caretaker)

Behind the scenes
"Another Brick in the Wall" is a song by Pink Floyd, from their 1979 album,. The song is a three-part composition describing several points where the album's protagonist, Pink, adds to the mental wall dividing himself from society: part one details the emotional effects of his father's death in World War II, part two details Pink's resentment towards the strictness of the 1950's British education that then-Pink Floyd lead Roger Waters dealt with in his own childhood, and part 3 details the completion of Pink's wall in light of the apparent revelation of his wife's infidelity. The song's second part, which is referenced in Doctor Who, is one of Pink Floyd's best-known works, despite it being remarkably different in style from the band's other works.