Released between 2002 and 2006, Big Finish Productions' Sarah Jane Smith series of audio dramas explored the life of Sarah Jane Smith in the years after she was left on Earth by the Doctor. The series took place in the present day, and apparently after the events of the television story A Girl's Best Friend. K9 Mark III did not appear in these stories, as he had broken down and was in a box in Sarah Jane's attic; he was dismantled by Hilda Winters when she found the box.
The final episode of the series, Dreamland, was released only a few weeks before Sladen returned to Doctor Who as Sarah Jane in School Reunion. This return to Doctor Who led to the commissioning of a new TV spin-off series, The Sarah Jane Adventures, which in turn resulted in the Big Finish audio series terminating after nine stories.
The TV continuation does reference the events of the audios, i.e. School Reunion revealed that K9 had been non-functional for some time. There is also mention of Aunt Lavinia leaving Sarah the house. (TV: The Wedding of Sarah Jane Smith)
- Sarah Jane Smith — Elisabeth Sladen
- Josh Townsend — Jeremy James
- Natalie Redfern — Sadie Miller
- Ellie Martin — Juliet Warner (Series 1)
- Will Sullivan — Tom Chadbon (Series 2)
- Sir Donald Wakefield — Stephen Greif (Series 2)
- Early in this series, Sarah Jane drove a red Volkswagen Beetle called Ethel.
- The character of Ellie was originally intended to be the Eighth Doctor's former companion Samantha Jones who had remained behind with Sarah Jane after PROSE: Interference - Book Two.
- Besides Sarah Jane herself, Hilda Winters is the only other character from the classic series to appear in Sarah Jane Smith.
- Sarah Jane and Josh are the only characters to appear in all nine audio dramas in the series.