Unofficial figures show that episode seven of Series Four, The Unicorn and the Wasp, was watched by 7.7 million viewers, giving it a 36.1% share of the total television audience.
The programme was helped by a later start and wet weather across much of the United Kingdom and achieved an increase of over a million on last week's figures.
The top rated programme was still ITV1's Britain's Got Talent with 8.6 million. Doctor Who was the highest rated programme on BBC1 for the day, beating Casualty by 1.3 million.
The programme is currently the 8th most watched of the week, almost guaranteeing a final Top ten place. Final figures will be released by BARB in ten days time.