Miss Erehwon's ship
Miss Erehwon's ship (PROSE: Set Up to Blow Up) was a TARDIS stolen from Gallifrey in the 89067986779811167562948736197891674912223184th Universe by an incarnation of Jenny Nowhere. (PROSE: How To Steal Timeships & To Influence Time Lords)
Biography
Theft by Jenny Nowhere
This TARDIS was sitting in the Old Workshops on Gallifrey, in its undisguised form as a silver column, when this universe's First Doctor arrived, intending to make his escape. Unbeknownst to him, the Great Intelligence had possessed the ship a “few hours” before he got there. Although able to take control of the ship from within, the Intelligence didn't know how to pilot it, only being able to “hardwire the desktop theme to Semple Black", which would render it impossible for a normal humanoid to control as the pocket universe containing the ship's interior was plunged into a pitch darkness (PROSE: How To Steal Timeships & To Influence Time Lords) broken up only by an “intensely pink” message which periodically appear to demand that visitors disavow all connection to Anish Kapoor. (PROSE: Set Up to Blow Up)
However, an incarnation of Jenny Nowhere also arrived in the Workshops to head him off. Nowhere intended to steal the local version of the Doctor's TARDIS before he himself could do so, thus usurping its metafictional “mythic power”. Unaware of the wrinkle the Intelligence's machinations had added to the tale of the Doctor's escape, however, she knocked out the Junior Time Technician fated to advise the Doctor against stealing the first TARDIS he saw, and to point him at the “right” one. Getting confirmation from the Doctor that the TARDIS he was looking at was the one which, until that moment, he'd been intending to steal, Nowhere stole it for herself, and took off into the Time Vortex, making herself glow with shifting power to see the controls. After the Intelligence revealed itself, and they realised their mistake, they decided to land somewhere quiet and work out an arrangement. Meanwhile, history resolved itself as the Doctor made for the correct TARDIS after all. (PROSE: How To Steal Timeships & To Influence Time Lords)
Later events
“Miss Erehwon” continued to use this ship, whose interior stayed pitch-black, as she travelled in furtherance of other, unrelated evil schemes. On one occasion, she landed within the Backrooms in the 925th Universe, specifically inside Dynamite Thor's Secret Headquarters. There, the ship disguised itself as a Kerblamazon Therapy Prism identical to the one which stood near the entrance of the Headquarters. After his chat with Erehwon, Thor briefly stumbled into the ship, and glimpsed the pink warning, but was soon ushered out again by an irritated Erehwon and thought no more of it as the second Prism vanished with a distinctive groaning sound. (PROSE: Set Up to Blow Up)
Behind the scenes
Miss Erehwon's ship was implied to be a TARDIS with a working chameleon circuit in its debut within PROSE: Set Up to Blow Up, but was not positively identified as such for copyright reasons.
PROSE: How To Steal Timeships & To Influence Time Lords, a fanfic prequel authored by Aristide Twain and endorsed by Set Up to Blow Up author Scott Sanford, made the connection explicit and further suggested that this TARDIS was its world's equivalent of the one which a splinter of Clara Oswald advises the First Doctor against stealing in a flashback scene in the 2013 TV story The Name of the Doctor.
All of the Clara Oswald splinters were working to counteract various sabotage attempts made throughout the Doctor's timeline by splinters of the Great Intelligence, but the specifics were not clarified; How To Steal Timeships… proposes that the local splinter of the Intelligence had outright possessed the “wrong” TARDIS, hence the need for Clara to point the Doctor towards another ship.
