Kill or Cure was a hit and miss method of curing fevers in the eighteenth and nineteenth century, in which the patient was plunged into cold water repeatedly until they either died of the shock or their temperature came down to a safe level. It’s hit and miss, of course. How many patients survived, how many died, is probably not known. The same kind of idea in a space age variety was seen in the Doctor Who episode, Terminus. The victims of disease were subjected to unregulated levels of radiation. Some were cured, some died. Nyssa realised that, if it was properly regulated it would work like radio-therapy for cancer victims, but until then it had been crude and ineffective.

When Lily contracts measles while staying on Earth in January, kill or cure is the only way to save her. Marion, Kristoph and Li have to subject her to the freezing bath of water and then bring her back to bed and hope that it works. Meantime she is surprisingly delirious. Marion discovers some hitherto unknown facts about her youthful relationship with Kristoph. She also finds out that, just as you can take a man out of Liverpool but not Liverpool out of the man, you can’t take a Time Lord out of Gallifrey....

But we all knew that, of course!