Jaems,
my first thought was that I had overseen the cigaret lighter - I'm a non-smoker for many many years now - and I wanted to say: you are right again Jeams, sorry!
But, checked my early 3-clock wiring diagram and found the cigaret lighter to be powered by a red/grey wire... However, you might be right. Perhaps I can find some under dash pics from my '65/'66 restoration, which is a quite original car as you know.
This is what my circuit diagram shows - no color correction ...
Otto