It’s amazing how well the pacing of a 6 parter fares when the story is split into two distinct sections. Here we are treated to an initial two episode burst at a polar icecap, acting as a tragic origin story for the Krynoid’s discovery on Earth. Satisfyingly for the narrative, The Doctor only achieves a partial victory at the end of part two. The first Krynoid is destroyed, but all the innocent people on the polar base are killed by one of Doctor Who’s all time great henchmen Corby. It’s sister pod is also stolen and makes it’s way back to another top tier villain (Harrison Chase) to the very different setting of the English countryside for parts 3 to 6.

A lot of what occurs in the middle of the story is a runaround, with The Doctor and Sarah-Jane falling in and out of trouble and the establishment of another Krynoid, but it’s written with such skill that you never feel like the story is treading water - there is an propulsive energy to the production. Critically, whereas the first time this threat emerged they were in the middle of nowhere, closer to civilisation, this threat becomes potentially apocalyptic.

Harrison Chase is what makes the last third of this story really shine, giving a human face to the menace. His key character trait is that image is fanatical about plants, an unhealthy obsession that he would put ahead of anything else - even humanity. Whilst your bog standard Who villain would have been rallying guards and begging the monster of the week to not kill them, Chase is fascinated in the developing menace, taking photos of it and delighting in its power.

Whilst Terror of the Zygons was a good story, The Seeds of Doom confirms Robert Banks Stuart to be an absolute master at writing Doctor Who. It is such a pity that we only have one last script left from him to enjoy. This story is another all time classic continuing Tom Baker’s superb run as The Doctor.