During his one series as the Doctor, Christopher was joined by Billie Piper who starred as companion Rose Tyler.
Christopher previously turned down the opportunity to return as the Ninth Doctor for the show’s 50th anniversary special in 2013.
The Day of the Doctor saw Matt Smith as the Eleventh Doctor and Jenna Coleman as companion Clara Oswald.
The Tenth Doctor David Tennant and Billie reprised their roles for the anniversary special.
Doctor Who can be streamed now on BBC iPlayer and BritBox.