I stumbled across this interview Elisabeth Sladen (and her friend K-9) gave on the BBC kids' show, Blue Peter— at this point, Sladen had returned to the Doctor Who franchise for an episode titled "School Reunion" (2006), in which Sarah Jane finally confronts the Doctor for leaving her behind on Earth. I do believe this interview occurred before The Sarah Jane Adventures even existed, a series that secured her place as the most popular companion known to the Doctor Who universe. I thought the clip offered great insight into the warmth and sweetness Sladen possessed that became her trademark as the clever, motivated Sarah Jane. (In addition, you get a glimpse into an odd TARDIS-based kids' craft):
She will be deeply missed across the generations of Doctor Who fans. Rest in peace, Elisabeth Sladen.