This pretty blue old-fashioned police box looks very similar to the one that the TARDIS appears to be.
The Doctor: I don't understand. Who are you?
The Doctor: The TARDIS?
Idris: Time and Relative Dimension in Space. Yes that's it. Names are funny. It's me. I'm the TARDIS.
The Doctor: No you're not! You're a bitey mad lady. The TARDIS is up-and-downy stuff in a big blue box.
Idris: Yes, that's me. A type 40 TARDIS. I was already a museum piece when you were young. And the first time you touched my console, you saidâ��
The Doctor: I said you were the most beautiful thing I'd ever known.
Idris: Then you stole me. And I stole you.
-- "The Doctor's Wife" (Series 6, Episode 4)