‘I’m over, my story is finished. But this planet, it needs someone to protect it. Are you that person?’ Through no fault of the writers, this is a very hard watch indeed. Seeing Sarah Jane being told, ‘You are very ill indeed’ and watching her deteriorate, knowing what’s just around the corner, pushes this beyond the unsettling intent, and makes it upsetting. It’s even worse because Sladen performs a fading Sarah, losing her memories (even K9) and her sense of self, predictably well. Real life has made this all too real.

If you can put that aside, this is excellent. Pitting Sarah Jane against her own Master, her equal and opposite, is a fantastic idea. The show flirted with it before, with Mrs Wormwood, but Ruby White takes it to the next level: a character consciously based in Sarah Jane’s life, with her own (pocket sized) supercomputer. She’s played by Julie Graham, an actor ubiquitous around the turn of the 2010s, and who really knows what she’s doing. When she’s playing up to the Sarah Jane archetype she’s warm, engaging and fun, insinuating herself into Rani and Clyde’s lives, even giving Rani driving lessons as Sarah Jane watches forlornly from the side-lines (helped by the direction which increasingly favours Ruby over Sarah). When Ruby turns, she’s cold and cruel. She’s a more promising recurring nemesis than the Trickster.

Next Time: Goodbye, Sarah Jane Smith – Part Two