Thanks eribanaut! This makes sense, is this because the van is of a foreign make.
If I wasn't clear with my first posting; regardless whether we are coupled up to the car or not our awning light doesn't work. As soon as I connect the EHU lead and turn on the awning light switch inside the van it works. If I then disconnect the on board 12v battery the awning light goes out (EHU still connected). So clearly the light does get it's power from the on board battery but appears to be relay tripped via EHU.
I agree with what pmb says, although because our awning light doesn't work unless connected to EHU we have an alternative.
And our alternative light most certainly won't be left on while driving; It would look pretty silly driving along with the awning attached. :silly: