The overnight rating is the lowest the series has received in its history, just below that received by The Lie of the Land, which was up against the Britain's Got Talent final.
Doctor Who faired relatively well compared to other programmes on Saturday with all suffering from the good weather across the UK on Saturday with the highest rated programme, BBC News, getting just 4.09 million watching. Casualty had 3.75 million while Mrs Brown's Boys had 3.40 million. Pitch Battle, which followed Doctor Who had just 2.03 million watching.
ITV peaked with just 3.11 million viewers for The Voice Kids, while the film Bridget Jones: The Edge of Reason had just 1.60 million viewers.
Final figures which will include those who recorded the programme and watched it later, will be published next week.