Update #24
Last night I did a quick test of cleaning auto wax, dirt, etc. off the black trim on the boot handle mechanism.
Before:
To clean I simply used hot water with some regular liquid hand soap in it and I carefully scrubbed the black plastic parts with a toothbrush. The heat and soap helps soften and lift the wax. I then used a cotton cloth soaked in the hot water and soap to wipe away the remaining wax. Had to go over a few spots a second time, but I'm really pleased with how well this has cleaned up.
After:
I've got lots more to clean, and I want to go through and remove the extra wiring from when the first owner of the car had a tow bar installed.
I'm also still trying to decide whether I attempt to restore the surface of the reversing light enclosures or whether I just buy new ones. Looking at them it looks as though the plastic may be started to fracture and degrade beyond the surface layer, so may just be better to buy new ones.
I've also got a couple of bits and pieces on order from Milland for the front of the car, so I'll update when they arrive.