Everyone talks about Emelia Rumford, who is one of the triumvirate of brilliantly batty old ladies in the Tom Baker years. But Susan Engel’s performance is superb. In a series that – to this point – has had vanishingly few female baddies, she sets the benchmark. Vivien Fay is playful and teasing, even flirtatious, but with a brutal streak and the sense that, like Richard III, she really rather enjoys being evil. Missy is basically Vivien Fay turned up to 11. The scene where she half-botheredly tries to nix Romana’s plans to investigate the Nine Travellers while sipping tea is brilliant.

Meanwhile, Tom gets his long-time wish for a geriatric companion as he and Emilia investigate the De Vries house and discover a priest hole full of portraits of Vivien Fay in her previous incarnations. These sequences strike a rather impressive balance between being funny and being creepy. De Vries and Martha’s death by Ogri, as an alien rock smashes into the cosy domesticity of their second-home satanism, is one of the few scenes in Doctor Who that might make you laugh and shudder. And the aftermath – the glimpse of De Vries’ corpse (we’re spared sight of his skull crushed to pulp) – is very nasty, and Baker wisely does a bit of funny business covering K9’s eye to lighten it a bit. Also creepy: the feathered Cailleach, taloned claws tipping a bowl of blood to feed a hungry Ogri.

In general, I think this is great, a much more convincing “Williams in the style of Hinchcliffe” than Image of the Fendahl (the exception being the day-for-night filming, which isn’t a patch on Fendahl’s genuine night-time location work). It’s making much greater use of the Key of Time plot than the previous two serials (with the search for the segment driving much of Romana’s plot). And after being a bit of an afterthought in most of Season 15, K9 is coming into his own this year. This begins the trend (which became a bit tiresome in Season 18) of having him smashed up, presumably because a section of the audience were more invested in what happened to the dog than the Time Lords.

Next episode: The Stones of Blood – Part Three