Doctor Who...in colour!
Just as The War Games was a full stop finale to all that was 1960s Doctor Who, Spearhead From Space is such a massive reboot of the series look and format that it is scarcely recognizable from the black and white era that came before it. New Doctor, new companion, new format, new titles, and, of course, in colour. This story is also a massive cheat.
When I first saw this story back in 1990, it came after having watched, in order, from the early Tom Baker era all the way through until the end of the Sylvester McCoy era. Then, the local PBS station started back at the beginning, which, in their eyes, was the Jon Pertwee era. I was amazed at the look of the programme. The fact that a union strike forced this story to be shot entirely on location was both a blessing and a curse. Let's set the record straight about this story, particularly Episode One - it looks fantastic. This is a fleeting glimpse at what Doctor Who could be if it was made as a film series instead of in front of a multi-camera setup in a crowded BBC TV studio. Alas, we would never see this look again in the classic series.
Other things that will become familiar to us - The Doctor and UNIT - are lightly introduced in this episode, with the identity of the new Doctor being kept deliberately vague until we, along with The Brigadier, the only other person, apart from the viewer, who should be able recognize him, see his face for the first time midway through the episode. In what is becoming typical Robert Holmes fashion, the writer is much more keen to (and quite good at) setting up the story and introducing the vast array of characters that will flesh out the plot before The Doctor and his soon to be new UNIT friends get themselves involved.
A superb start to the 1970s.