Steven Taylor held possession of a TARDIS key.[source needed]
After the departure of Susan Foreman, the Doctor was left without a spare for a time. (PROSE: The Plotters) When he met them, the Fifth Doctor was surprised that both Steven and Vicki Pallister lacked TARDIS keys and said that they should have one. (AUDIO: The Secret History)
Early in his travels, the subject of whether Steven should get a key was a subject of much contention among himself and the First Doctor as the latter didn't trust him. The only thing they agreed upon was that Vicki shouldn't have one. After an adventure involving William Shakespeare in 1609, the Doctor promised to give him a key (PROSE: The Empire of Glass) but he still had not received one by the time of the pair's travels with Oliver Harper. (AUDIO: The Cold Equations)
In an alternate timeline[which?] created by a temporal collision of the First and Second Doctor's TARDISes, Steven remarked that he still hadn't received a TARDIS key, annoyed that Katarina had already been given one. (AUDIO: Daughter of the Gods)