The Evil of the Daleks - S4-E9
Trivia: The Doctor only appears in pre-filmed insert scenes for the fourth episode, as Patrick Troughton was taking a holiday during production.
Trivia: In the animated version of this story, when we're at the police station, there are some wanted posters on the wall in the background. One of the wanted posters is for the original Master, Roger Delgado.
Answer: TARDISes are generally available for properly authorised use on Gallifrey; they're not usually assigned to a particular Timelord on a long-term basis. The Doctor stole his when he left his homeworld.
Tailkinker ★