Most of the cue cards that Clara leaves for the Doctor in Under The Lake make some sort of sense, such as "I didn't mean to imply that I don't care," and "I completely understand why it was difficult not to get captured." Another one, however, might need a little bit more explaining. As seen in the image above, it reads: "It was my fault, I should have known you didn't live in Aberdeen." This refers to the Fourth Doctor dropping companion Sarah Jane off somewhere that wasn't her home town, later confirmed in episode School Reunion to have been Aberdeen.