4.85 million viewers watched Doctor Who: The Girl Who Died, according to unofficial overnight viewing figures.
Doctor Who was the second highest rated show of the day, behind Strictly Come Dancing which had an average of 9.66 million viewers. Casualty was third with 4.61 million watching.
Rugby scored highest on ITV, but with none of the home countries playing, just 4.04 million watched New Zealand defeat France.
The rating, the highest figure for the series this year, was slightly boosted by the late start to the episode, meaning the calculation includes the remnants of the Strictly audience. However detailed figures show the audience rising during the show once the Strictly audience had departed to average around 4.63 million.
Final ratings will be issued next week, which will be based on the exact transmission time for the episode and will include those who record it and watch it later.
Doctor Who is currently the 22nd most watched programme for the week