Anthony Head has also appeared in two of the BBC's animated Doctor Who adventures - Death Comes To Time and The Infinite Quest. He auditioned for the part of the Eighth Doctor and also narrates Doctor Who Confidential.
A Girl's Best Friend
Sarah Jane was not given K9 in a Doctor Who adventure, but the one and only episode of its first spin-off, K9 And Company.
You probably recognise which stories Rose is referring to in her bragging match with Sarah Jane, but how about the ones Sarah Jane mentions? Death To The Daleks (1974) and Genesis Of The Daleks (1975) for the Daleks, Robot, The Sontaran Experiment and The Android Invasion (all 1975) for "lots of robots", Planet Of Evil (1975) for anti-matter monsters, Pyramids Of Mars (1975) for mummies, Invasion Of The Dinosaurs (1974) for dinosaurs, and Terror Of The Zygons (1975) for the Loch Ness Monster.
Working titles for the story included Old Friends and Black Ops.
Two Welsh high schools were used for filming: Fitzalan High School in Leckwith and Duffryn High School in Newport.
Bit Part, Or Big Part?
Actress Elisabeth Sladen initially turned down the chance to resurrect Sarah Jane, mistakenly thinking that she was only being offered a cameo role, rather than a major one.
The aged K9 prop is based on an original lightweight body shell used in the 1970s and 1980s, when he had to be carried by actors. The rebuilt version is the proper radio controlled version last seen in Dimensions in Time and owned by former BBC Special Effects designer Mat Irvine.
Anthony Head reprised his role as Mr Finch for a game based around the episode here on the Doctor Who website.
The Krillitanes were originally called Krillians, until it was discovered that the name was trademarked.
The Write Stuff
Writer Toby Whithouse went on to pen the Torchwood episode Greeks Bearing Gifts.