"Aliens of London" is the fourth episode of the first series of the British science fiction television show Doctor Who after its revival in 2005. First broadcast on 16 April 2005 on BBC One, it was written by Russell T Davies and directed by Keith Boak. It is the first in a two-part story, concluding with "World War Three". World War Three" is the fifth episode of the first series of the British science fiction television programme Doctor Who which was first broadcast on BBC One on 23 April 2005. It is the second of a two-part story which began with "Aliens of London" on 16 April.