Writer Steven Moffat stated that he wanted an " epic " quality to the Christmas special . The story would also show how the Doctor had responded to losing his previous companions ; Moffat said that " I think he 's probably reached the point in his life where he 's saying , ' Friendship for me is just postponed bereavement — I want to be on my own for a while ' . " Moffat compared the withdrawn Doctor seen at the onset of the episode to the first appearances of the First Doctor ( William Hartnell ) in 1963 and the Ninth Doctor ( Christopher Eccleston ) in 2005 . He also attributed the idea of a retired Doctor to a plot proposed by Douglas Adams in the 1970s , but rejected by the production team at the time . Continuing the theme introduced with the series ' first five episodes , " The Snowmen " was promoted like a movie . A movie poster was released in the Radio Times , showing the Doctor and Clara ascending the ladder to the TARDIS .