Hi tiddy,
The two connectors above the towbar are for trailer and caravan lights and power. The white on on the left (passenger side) is refered to as the 12S and is used in the EU for caravans and the like. It provides battery direct and ignition controlled power (Pins 4 & 6) plus reverse.
The black one on the right is for trailer lights (brake, turn, tail). There is a minor difference to the AU convention in that the tail lights are provided seperately (left and right). If you do not have electric trailer brakes this is not an issue. If you do then when you turn on the tail lights (or headlights) power is feed to the pin that we use for trailer brakes and brings them on. Big problem. There are a number of threads and an proven solution.
Hope that helps.

