My GLS has the twin sockets on the tow setup. Is there a live feed bypassing the ignition on the 2nd socket.
TIA. 
[edit]
Sounds stupid the way I re-read that back to my self. This is of course assuming that all 1st and 2nd sockets are of a standard wiring configuration.[/edit]
If you look at this diagram
http://www.electronics2000.co.uk/pin-out/trailer.phpIt shows a permanent live off pin 4 of the 12 S (grey).. this is what you use if the van is left connected to the car "overnight" - obvious danger is car battery gets flattened.
ALSO..... on newer vans that feed is controlled by a "habitation relay" fed from pin 6 of the 12S ... which should be ignition controlled ...
What this does is to switch OFF all internal electrics when the ignition is ON, and divert the power to the caravan battery charge circuit. when the ignition is OFF, the internals work but the battery charge circuit is disconnected.
The idea being twofold ..
1) ignition ON - The internals being off will "discourage" people travelling inside the van - illegal anyway !! - and the van battery is charged.
2) ignition OFF - A faulty van battery will not be connected to a good car battery and so drain it ( or vice-versa)
HTH