 Overnight figures estimated that the episode 's Christmas Day broadcast was watched by 12 @.@ 2 million viewers . The final viewing figures were 13 @.@ 31 million viewers with a peak of 13 @.@ 8 million , the second highest audience for any programme during 2007 : the episode of BBC soap EastEnders which aired after " Voyage of the Damned " was watched by 13 @.@ 9 million viewers . The viewing figure is the highest for the new series , exceeding the previous record set by " Rose " . The figure is also the highest for Doctor Who overall since 1979 , specifically , the final episode of " City of Death " . The episode 's Appreciation Index rating was 86 ( " excellent " ) , above the average score of 77 for drama programmes , and was the highest Index rating for any programme shown on terrestrial television on Christmas Day . Although not filmed in HD , the BBC aired it on BBC One HD , Wednesday 29 December 2010 , having up @-@ scaled the program to HD and also including Dolby Surround sound . This is the first Doctor Who episode , filmed in SD , to have been up @-@ scaled to HD for broadcast on television , and the second episode , overall , to be up @-@ scaled from SD to HD , the first being the 2008 Christmas Special , The Next Doctor , for the Blu @-@ ray release of the Complete Specials Boxset . 
