 Building upon the character 's surprise introduction in " Asylum of the <unk> " , " The <unk> " introduces <unk> as the Doctor 's new companion , though ultimately it would be a third version of her character that would travel with the Doctor starting with " The Bells of Saint John " . In addition to <unk> , " The <unk> " also introduces a redesigned <unk> , revised title sequence and theme music , and sees changes to the Doctor 's costume . The special was produced in August 2012 , with location filming in Newport , Wales and Bristol . It received final ratings of 9 @.@ 87 million viewers in the UK , becoming the fourth most @-@ watched programme of Christmas Day . " The <unk> " was met with mostly positive reviews from critics , most of whom received the introduction and character of <unk> well . However , some felt that Grant and <unk> were <unk> as villains or the plot was slight because of the focus on characterisation . 
