Except it's not in a 46-year history, it's in a ... what... 5 year history? Maybe 6?
No, Doctor Who debuted in November 1963, the current show is a continuation of that, not a reboot (THough there was that little gap between 1989 and 2004 with a small blip in the form of the McGann movie in 1996). K-9 and Sarah Jane both made their debuts and names back in the 1970's (and almost got a spinoff there, the only attempt that it had had at a spinoff in it's history until Torchwood). The spin-off resulted from the recent appearances, but the reason they were so popular dates back 30 odd years...