Wish You Were Here

"Wish You Were Here" was a song the Twelfth Doctor began playing on the electric guitar in his TARDIS after he and Ashildr made peace with each other. (TV: The Woman Who Lived)

Behind the scenes
Although not mentioned by name, the song's intro is recognisable. "Wish You Were Here" is a song by Pink Floyd; the song is one of the band's many reflections on their former frontman, Syd Barret, and the mental illness that forced him to leave the group in 1968.