Chronotis's TARDIS

Professor Chronotis' TARDIS was disguised as the residence of Professor Reg Chronotis at St. Cedd's College, Cambridge University. It was capable of holding another TARDIS within its force field and of creating a bridge between the two to walk through.

This TARDIS was a Type 39 TARDIS, a much earlier version than the Doctor's Type 40; it could interfere in an individual's time stream. (DW: Shada, WC: Shada, BFA: Shada)