 The episode includes several references to outside the show 's fictional universe : the episode is dedicated to Verity Lambert , Doctor Who 's founding producer , who died on 22 November 2007 , a day before the show 's forty @-@ fourth anniversary ; and the malfunctioning Host stuttering over the name " Max " is a reference to 1980s virtual presenter Max Headroom ; Davies inserted references to other Doctor Who episodes in the script : he emphasised society 's increasing awareness of aliens and the tradition of London 's consecutive Christmas attacks in the script , describing the latter as " becoming a bit of an in @-@ joke " ; the Doctor 's use of the catchphrase " <unk> @-@ y Alonso " in the episode when he helps Frame stabilise the ship continues a running gag originating in " Army of Ghosts " ; and the Host continue the thematic motif of angels . Angels previously appeared in " Blink " , where the antagonists of the episode were Weeping Angels , and in " The Sound of Drums " and " Last of the Time Lords " , where the Master 's communication network was called the " Archangel Network " . Despite angels being the antagonist in two episodes that aired close to each other , which dismayed writer and executive producer Russell T Davies when he read Steven Moffat 's script for " Blink " , the Host are functionally different as subordinate " robot butlers " . 
