South Croydon was a London suburb. It was the home of Sarah Jane Smith and her aunt Lavinia when Sarah Jane travelled with the Doctor in his third and fourth incarnations. Sarah Jane asked the Fourth Doctor to drop her there when he took her home to Earth. (TV: The Hand of Fear) He mistakenly took her instead to Aberdeen, Scotland. (TV: School Reunion)
K-9 Mark III was delivered to Lavinia's home in a crate for Sarah Jane in 1978. Sarah Jane had already moved out of the house by that time and was travelling extensively. (TV: A Girl's Best Friend)
Dr Lavinia Smith left South Croydon in 1979, buying a manor house in Moreton Harwood. She took K-9 there, still in his crate, where Sarah Jane finally received him in December 1981. (TV: A Girl's Best Friend)
The location of Sarah Jane's and K-9's semi-detached house in 1983 is unspecified on-screen, although filmed in the London suburb of Uxbridge.[1] (TV: The Five Doctors)
Sarah Jane eventually settled in another London suburb, Ealing. (TV: Invasion of the Bane)
