Doctor Who - Thin Ice had an overnight viewing audience of 3.76 million viewers, a share of 20.4% of the total TV audience, according to unofficial figures.
Top for the day was ITV's Britains's Got Talent, which had 8.27 million watching. Top on BBC One was the comedy series All Round to Mrs Brown's with 4.74 million viewers. Casualty just edged ahead of Doctor Who with 3.90 million, pushing Doctor Who into fourth place for the day, just ahead of Pointless Celebrities which had 3.73 million.
Final figures will be released next week, which should see Doctor Who increase its audience substantially.