Chronotis's TARDIS

Professor Chronotis' TARDIS was disguised as his rooms at St. Cedd's College at Cambridge University.

It was capable of holding a TARDIS within a force field and creating a bridge between the two to walk through.

It was a much earlier version than the Doctor's Type 40, and as such could interfere in an individual's time stream. (DW: Shada, WC: Shada, BFA: Shada).