After the Doctor and Ian (and no doubt the audience) were surprised by the Dalek emerging from the Thames, they’re taken to the Dalek saucer at Chelsea.  Another prisoner, Craddock (Michael Goldie) explains how the Daleks invaded.

CRADDOCK: Well, the meteorites came first. The Earth was bombarded with them about…ten years ago. ‘Cosmic storm’ the scientists called it! Well, the meteorites stopped, everything settled down, and then … people began to die of this new kind of plague.
DOCTOR: Yes, that explains your poster, dear boy. Germ bombs, hmm?
CRADDOCK: Yeah, the Daleks were up in the sky just waiting for Earth to get weaker. Whole continents of people were wiped out. Asia, Africa, South America. They used to say the Earth had a smell of death about it.
IAN: Why Craddock? What were the doctor’s and the scientists doing about it?
CRADDOCK: Ah, well, they came up with some new kind of drug, but it was too late then.

This scene intercuts with David Campbell (Peter Fraser) telling Susan and Barbara the same story.

SUSAN: What happened next?
DAVID CAMPBELL: Well, the plague had split the world into tiny little communities. Too far apart to combine and fight and too small individually to stand any chance against invasion.
BARBARA: Divide and conquer?
DAVID CAMPBELL: Mmm. About six months after the meteorite fall, that’s when the saucers landed.

Nation’s draft scripts gave a different version of events. In the late twentieth century, the world was at war – China, Russia and America were at loggerheads whilst Britain was in conflict with Europe. But the arrival of the Daleks meant that the world united to face this common threat and a world government was formed in Japan.  The main problem with this scenario is that it would have begged the question as to exactly what the Daleks had been up to on Earth for the past two hundred years!

When Nation started crafting a sequel to The Daleks, his first thought was about how he could raise the stakes.  Showing the Daleks as the masters of Earth was an obvious choice – Jon Pertwee’s oft repeated comment about finding a Yeti using a public convenience in Tooting Bec demonstrates how mixing the everyday with the unknown can be a powerful one.  The Dalek/Thal conflict on Skaro worked well, but juxtaposing the Daleks with the familiar Earth landscape offered many more dramatic possibilities.  Of course you have to find a good reason as to why the Daleks would travel across the universe to invade the Earth.  Did Nation succeed? Mmmm.

Over the decades Earth would find itself under attack from a whole host of marauding aliens – but it’s rather fitting that the Daleks, given their status in the series, were the first.  They’re also by far the most successful, since subsequent invasions almost always happen when the Doctor is around, meaning that he’s able to save the day before things get too far out of hand.  Here, the invasion’s over and the Daleks have achieved a complete victory.  Humanity has been decimated and the survivors have been reduced to living underground or on the run, waging a seemingly hopeless struggle against an all-powerful enemy.

Nation’s memories of WW2 come to the fore in this episode, especially with the Daleks’ radio broadcast. “Rebels of London. This is our last offer. Our final warning. Leave your hiding places. Show yourselves in the open streets. You will be fed and watered. Work is needed from you but the Daleks offer you life.”

Susan and Barbara have made contact with the rebels. They’re all fairly broad character types, but luckily Richard Martin found good actors who were able to put a little meat on their bones.  Dortmunn (Alan Judd) is the wheelchair bound inventor who’s convinced he’s developed a bomb to destroy the Daleks – we’ll shortly see how terribly wrong he is.  Jenny (Ann Davies) is a hard as nails survivor who, no surprise, becomes more human as the serial develops.  Tyler (Bernard Kay) doesn’t have a great deal to do in this episode, except argue with Dortmunn, but Kay (who would return to the several several times in the future) is always watchable.  And David Campbell will serve a very definite purpose in the story, although there’s no sign of that yet.

A late revision to the script concerned the intelligence test that the Daleks use to decide which humans are fit to be converted into Robomen.  In the first draft, the Daleks simply turned up and took their prisoners to be Robotised one by one.  This obviously wasn’t deemed to be satisfactory, so something more elaborate was created.  But it does beg the question as to why the Daleks bother with all this palaver – since the Robomen are seen to have no free will of their own, why do the Daleks need to select those of a certain intelligence?  This also means that a Dalek has to be present outside every cell, waiting for the prisoners to work out how to escape.  Surely this would tie up a lot of Daleks?  The Peter Cushing movie streamlined things considerably by showing Cushing’s Doctor using a comb to escape!

Technically, this episode is a little messy.  A member of the production team wanders in shot at one point and David Graham’s pre-recorded Dalek lines are cued in too early in one scene.  The rebels’ attack on the saucer doesn’t really convince either – had it been shot on film rather than VT then it could have been cut together more convincingly.