Whilst the majority of characters in this series call the journalist by her full name of Sarah Jane, in the original series it was more common for her to be addressed as just Sarah. This has been commented on in the series, where the Doctor notes she allows very few close friends (such as him) to use the diminutive.
CBBC originally approached Russell T Davies asking for a Doctor Who spinoff involving a young Doctor on Gallifrey. Davies rejected the idea, feeling it would take away from the "mystery" of the Doctor, and proposed this series after a positive experience working with Elisabeth Sladen in "School Reunion".
As "The Temptation of Sarah Jane Smith" reveals, the titular lead character was born in Foxgrove, Hertfordshire, to Eddie and Barbara Smith. Following their seemingly-inexplicable disappearance on Saturday 18th August 1951 (when SJS was three months old), her father's sister Lavinia raised her.
Amy Pond and Rory Williams (Karen Gillan and Amy Pond), companions of The Eleventh Doctor (Matt Smith) did not appear opposite The Eleventh Doctor in Death of the Doctor: Parts One and Two (#4.5) and (#4.6).
Sarah's final speech in the last ever episode The Man Who Never Was: Part Two (#5.6) is "I've seen amazing things out there in space, but strange things can happen wherever you are. I have learned that life on Earth can be an adventure too. In all the universe, I never expected to find a family."