So, underwhelmed by the responses (maybe you're all actually gainfully employed) I tackled the problem head-on. Nothing much holding me back, just a couple of deadlines that can wait!
First strip out one of the door switches and figure how it is supposed to work.
In the door open position the switch should be normally closed. Not much happening here.
So how to strip and get to the guts?
Drill out the three plastic posts..we'll need the holes for later.

Expose the workings.
Seems some of the contacts are broken
What it should look like
Slightly buggered
So with a bit of heat, bend the contacts back into something workable.
Clean up the tab on the earth-plate. Seems it's the major problem.
Slap the lot together, wire it closed (remember the holes), test that it opens when pressed. Fasten and repeat!
I can now confirm, as per clive, that the four side doors DO in fact operate the center light and the rear Hatch operates both the center and rear lights.
And just in case you were wondering, there's a micro-switch in there somewhere that operates the rear light.
Still don't know what this is or does!!!
