There are wires (and connectors) for rear speakers for cars without, aswell as rear boot courtesy lights... seems pointless to put a light in the boot, but its surprisingly handy, and will also be usefull for alarms with current sensing on them. The wire and connector for the switch is also in the tailgate

Finally, the "lights on audiable buzzer" relay needs an earth for it to work properly, due to it not being connected, but once again being there, with a connector. You just need the relay and a new drivers-side door switchfrom a car with the buzzer for it to work (the switch differs in that it has a second pin to attatch the buzzer ground too. (the wire is just inside the hole for the switch.

Suggestion submitted by Rob H