I am having a problem getting the plug and cable for the switch through the bonnet release cable hole.

I am using some wire as a means to pull it through, taped to the cable and plug with a small amount of gaffa tape, but even though I have bent a small amount of wire back toward the engine bay and taped over it well enough, I cannot get the damn thing through and the wire eventually separates from the plug / cable.

Maybe I will look at separating the plug from the cable and re-solder when the cable is through.

Any tips on getting it through without removing the plug?

Look at instructions 1 to 10 in the attached pdf that covers installation of the Aux Power Socket.

Done it.

Got it through the bonnet release cable rubber grommet with a smudge of Vaseline.

All Freelander owners should always carry a pot of Vaseline.
You never know when you will be in the presence of a tight hole!