Tegan Jovanka's TARDIS key

Tegan Jovanka held possession of a TARDIS key, given to her by the Fifth Doctor. (AUDIO: Hexagora)

Early in her travels with the Doctor, Tegan did not have a TARDIS key. When the TARDIS landed on Monarch's ship, she was given the Doctor's spare key in the event she was separated from the group. (TV: Four to Doomsday)