"Paperback Writer" was a song playing in a London café visited by the Second Doctor and Jamie on 20 July 1966. (TV: The Evil of the Daleks)
Behind the scenes
Though not identified in the episode, the Beatles were the originators of the tune. Unsurprisingly, rights issues prevented it from being included on the audiobook version of The Evil of the Daleks; it was replaced by another 1960s track, "Hold Tight", by Dave Dee, Dozy, Beaky, Mick and Tich. Because the particular episode in which it appeared is a missing one, and neither dialogue nor the novelisation make reference to it, the fact that the song is a part of the Doctor Who universe is largely forgotten.