TARDIS (Divided Loyalties)
During his years at the Academy, the First Doctor and his fellow students Rallon and Millennia travelled in a stolen Type 18 TARDIS away from Gallifrey in search of the Guardians. As the TARDIS was a far older model compared to what they were used to, Rallon didn't like the facilities the TARDIS offered in way of comfort, stating the Type 30 Mark III or the Type 35 would be much more suitable.
Instead of taking them in search of the Guardians, the Type 18 instead took them to the Celestial Toyroom instead where Rallon's body was taken over by the Toymaker, and Millennia was made into a living doll who became a servant to the Toymaker.
The Doctor took the TARDIS back to Gallifrey. (PROSE: Divided Loyalties)