The series stars Elisabeth Sladen as the journalist Sarah Jane Smith , who was a companion of the Third and Fourth Doctor in the classic Doctor Who series . Sladen played the original part of Sarah Jane from 1973 until 1976 .
The character of Sarah Jane , played by Sladen , appeared in Doctor Who from 1973 to 1976 , alongside Jon Pertwee as the Third Doctor and later Tom Baker as the Fourth Doctor .