"The Daleks in London", commissioned on 25 May 1971, was to be the final story of Season 9 in 1972, re-introducing the Daleks after a five-year absence. Little is known about the exact storyline of the six-part Robert Sloman serial, other than the fact that it would have had some similarities to "The Dalek Invasion of Earth", except set in contemporary London. This similarity caused the production team some concern, and producer Barry Letts eventually decided that he would rather start the series with a Dalek adventure instead of ending it with one. An unrelated submission by Louis Marks was therefore rewritten into "Day of the Daleks", and "The Time Monster" was then written and commissioned to replace the original series finale.