As the Thirteenth Doctor prepared to detonate the death particle to stop the Master and his army, she led her human friends to this TARDIS which she programmed to send them to 21st century Earth. The Doctor intended to sacrifice herself to save the universe from the Master while using the TARDIS to get everyone else to safety. However, Ko Sharmus followed her out to sacrifice himself instead to finish the job his resistance group had started when they had ended the Cybermen.
Upon materialising on Earth, the TARDIS's chameleon circuit caused it to take the form of a house. The Doctor's friends emerged and were left believing that the Doctor had perished, unaware that she had instead escaped Gallifrey in another TARDIS and captured by the Judoon shortly afterwards. (TV: The Timeless Children)
Over the next ten months, Yasmin Khan, Graham O'Brien and Ryan Sinclair returned to this TARDIS. It remained parked in the same location with the same disguise. Yaz in particular spent a lot of time in the TARDIS, thinking about the Doctor, compiling notes and trying to figure out how to use it. On New Year's Day 2021, Graham and Ryan discovered that she had also been sleeping there. There, they warned Yaz that old enemy Jack Robertson was involved with the Daleks and, with the Doctor imprisoned and fearing they'll never see her again, decided to investigate.
When the Doctor did escape from the prison, with help from former companion Captain Jack Harkness, she called the Death Squad Daleks in to exterminate the Defence Drones, she used this TARDIS to lure the Daleks into a trap, using its chameleon circuit to give it a police box exterior resembling her own. The Doctor programmed her "spare TARDIS" to travel, with the Daleks inside, to the heart of the Void. The TARDIS folded in on itself, destroying the Daleks. (TV: Revolution of the Daleks)
Behind the scenes
- This TARDIS's interior, along with the other, used the same design as that seen in Fugitive Doctor's TARDIS earlier this season, rather than a model more closely based on the First Doctor's, as previous BBC Wales stories had done for "classic" TARDISes.