at the rear right side, if you remove the plastic paneling you'll expose the wires that come from the tail gate and enter the main body.
This harness twists a little, two wires separate off and disappear up the roll bar - presumably for the interior light - and there's a multi-wire harness connector.
Mine is unplugged. The plug and the socket are just lying there next to each other not plugged in. Everything seems to work. I did not unplug it, though the shop may have when they added central locking.
On my '15 sport, there's no power to either of the plugs. I found that they run all the way to the plug on the passenger side under the glove box, but are not included in the harness from that plug to the fuse box. I installed a rear power point, which is how I found this out.