The above drawing of Cloudbase from the 1967 Captain Scarlet annual was done by artist Keith Watson.
This exploded view of Cloudbase was in that same annual. It is uncredited but I'm wondering whether or not it was Keith again, as a similar view can be seen in the 1967 Century 21 Make a Model of Cloudbase booklet, which, coincidently is exclusively illustrated by Keith Watson.
Anyone know for sure?
And here, Cloudbase done by Eric Eden,which I have to admit does lend support to Andy's theory.