Review of all 4 episodes:
Spearhead From Space marks perhaps the biggest combination of changes in Doctor Who history:
- the change from the Patrick Troughton era to the Jon Pertwee era.
- the change from black and white to colour.
- the change from constant time and space travelling to an exile leaving The Doctor stranded in contemporary Earth.
- the change from two or three traditional companions to a whole organisation (UNIT) regularly working with The Doctor.
These changes are made even more striking by the fact that Pertwee's Doctor, having been forced to regenerate as a punishment from the Time Lords and subsequently getting injured, spends much of the early part of the story inactive in a hospital bed. Yet the story manages to be interesting enough and contains enough action, humour and thrills to make this big transition go very successfully.
The story involves the new Doctor finding himself stranded on Earth and suffering from his regeneration then having to deal with an invasion attempt by the Nestene Consciousness using their power to control plastic and creating armies of shop dummies.
The production is a peach with a superb look (recorded beautifully on film rather than the usual video), excellent direction by Derek Martinus and thrilling special effects (shop dummies coming to life and attacking through shop windows etc.) believably and excitingly executed.
The story is brilliantly written by Robert Holmes with superb plotting and dialogue. The acting from Pertwee and the whole cast is impeccable. Nicholas Courtney (Brigadier Lethbridge Stewart) and Caroline John (Liz Shaw) do fantastically well in their roles beginning already to get audiences to strongly sympathise and relate to them.
It is not absolutely perfect but it is perfectly entertaining and interesting with thrilling, scary moments. All 4 Episodes 10/10.