Once again, I feel like repeating that Doctor Who never really learned the lessons it was supposed to learn as a science fiction series. The production team should have figured out that their budgets were suited to small-scale psychological dramas set in various periods of Earth's history. They had a great cast suited to psychological drama, and they had set designers and costumers all over the place who had plenty of experience in making historical dramas on the cheap. Sure, Doctor Who was nominally science fiction, but making true science fiction of the scope that they envisioned was a ludicrous dream. 'The Daleks' showed it, especially in the final battle sequence...and yet, they never did learn to stop being ambitious. And thank goodness for that.
'The Velvet Web' is a perfect example. Terry Nation writes an episode that a) requires a number of sumptuous sets and costumes, b) cunning perspective shifts as Barbara resists the Morphos' brainwashing and sees the real world while her friends continue to see the illusion, and then c) the inner sanctum of the hideous brain-creatures, which gets destroyed in a spectacular action sequence as Barbara smashes it to pieces and the brain-creatures melt and die. The budget they have allowed for approximately three-fourths of a, one-third of c, and b would have been apocalyptically difficult even with a vast budget, thanks to the limits of film editing techniques in those days.
And did that stop them? No It Did Not. Ray Cusick, the BBC staff designer, threw himself gamely into the impossible task of realizing everything in Nation's script, and the regular cast swallowed their dignity and pretended that a dirty coffee mug was a cyclotron with the greatest of enthusiasm. And they made something that at least approximated the vision Terry Nation had when he sat down at his typewriter, albeit one that was never intended to be seen again at all, let alone watched on pristine DVD with all its faults revealed to the world.
And once the memory has glossed over the a's and the b's and the c's and Ray Cusick's desperation and the cast's embarrassment and time has turned what was actually on the screen into a potent blend of imagination and reality, you can see it for what it was intended to be rather than what it was. You can see the weird, paranoiac horror Barbara experiences as she tries to convince her friends of the shabby, dingy reality all around them while they caress rags and drink filthy water. You can sympathize with her plight, alone among an entire city that hunts her with a single-minded purpose for unknown reasons. You can shiver at the way that Ian almost absentmindedly tries to strangle Barbara, vividly and convincingly portrayed by William Russell. You can even be impressed when you remember that this is all just one city on the planet of Marinus, a science-fiction planet that's astonishingly enough not shown as a monoculture or a Manichean struggle between the oppressed and the oppressors, which is quite nice for a change. You can actually be quite impressed by this one...when you're not actually, you know, watching it.