Doctor Who: 8 Big Questions After Time Heist

8. Who Was The Woman Who Gave Clara The Doctor's Phone Number?

Time Heist addressed an on-going plot thread that runs all the way back to Clara Prime's introduction in The Bells Of Saint John; just who was the woman who gave Clara the number for the TARDIS? At the beginning of episode, the phone on the outside of the TARDIS began to ring, something which was a surprise to the Doctor who noted that very few people have his phone number. It was interesting to see the question of who that woman was hadn't been forgotten and that the Doctor, in asking Clara who she was, was still intrigued. And so are we. Clara obviously didn't recognise her, so it wasn't another version of herself. Nor - as we may have suspected at the time - was it River Song; otherwise Clara probably would have said something when she met the Doctor's wife in The Name Of The Doctor. Bringing it up now, perhaps the mysterious Missy is that woman? We have to assume we'll get the answer to that little mystery some day and maybe the Doctor's question suggests we'll get it sooner or later. Just who is important enough to have the Doctor's number?