Watched Doctor Who and Doctor Who Confidential just before typing this entry and it was excellent. The rumours I had heard weeks ago and strands of storyline from early in this series have finally come together. The rumour was that John Simm, fresh from Life on Mars, was going to be The Master. It was true but the twist did not come till the end of the episode.
Derek Jacobi was brilliant as ever as the kindly, mad but ill professor who later turned out to be The Master who had forgotten who he was with a watch identical to the Doctor's with him inside. There has been a mysterious Mr Saxon present from the beginning of this series telling Martha's family all sorts of stories about The Doctor to discredit him. Mr Saxon is probably The Master's alias with the this episode set before The Master went back in time to the present.
Looking forward to next week.