Matt,
Just read through your post, the red park light should go out after 20 mins. My old Vogue had 3 different battery drains over the time I had it. The first being water getting into the sat nav unit in the rear, which was cured by stopping the slight water leak fromt eh rear quarter glass and replacing the sat nav player. The second was the wiring harness which leads from the HVAC up under the drivers side lower panel and the third and last drain was cured by fitting a new heater hedgehog thing as someone else posted earlier in this link.
That was a bast@rd to get at with my big hands, I think I have a replacement harness in the garage as the second and third drains were linked, I just disturbed the heater controller thing swapping the harness over which cured the fault temporarily. The harness I took out of mine was the upgraded one (same part number and identical to look at) but when I went back to LR the final time, the parts guy said the most common cause for battery drain was this heater controller. Fitted that and it was fine for the last 6 months I owned it.
You're welcome to have this harness off me if you like, I'm only up in Chorley so cant be a million miles from you. Just PM if you want it and I can show you where the heater controller lives. I know small things like battery drain and over heating can be frustrating but stick with it, their great cars when running right......he says with holding his breath.
my air suspension went up the swanny at weeekend so have to fix that now. Id get your supplying dealer to pay for the new parts and get a trusted independent to fit them.
Mike