I also think it's important to point out what's shown on a wiring diagram can be different to what's actually present on a specific car, lets not lose sight of the fact these are hand made small volume production cars and of course there will have been RHD & LHD versions of the loom, this aside in my experience general loom variation is extremely common with such low volume artisan built vehicles.
I take your point Dave but
in this particular area not only do three iterations of wiring schematics as published by MMC over an eight year period concur but earlier and later ones do as well. Since around 2007 on there is only one loom variant to cover both left and right hand drive cars and to this end the brake fluid sensor and screen wash wiring is duplicated for each side.
Furthermore as mentioned you have found one end of this elusive blue/yellow wire colour coded specifically for front auxiliary lights. Where do you think this terminates and why would it be anywhere other than front of car with all the others as shown on the schematics?
The unused connector was a mystery until you pointed out it's under the n/s wing. It's almost certainly for optional Aircon and as can be seen is shown on close up schematic I posted labelled trinary switches. I have similar on my car.
So finally, everything you have found so far under wing concurs with wiring schematic.
