The plot thickens !!
Just spent the last 45 mins bailing out the boot. Under the boot liner, the carpet was wet and under the carpet/floor the spare wheel well was quite full. Had to do it with a sponge and kitchen roll and got 95% out. I have put spare wheel back and left the boot floor wedged up to allow air to circulate. I think that's where my condensation is coming from. The couple of litres of standing water in the boot!!!
I removed the RH side boot side panel and it was slightly damp in there, but that could have been condensed water from the main boot. Didn't seem sopping though and the battery was mainly dry. The LH side boot panel was bone dry. Both side panels seemed dry too. The boot-lid lining was damp, but again could be from condensation. No damp on headlining either, so I'm not sure it's coming from roof, but still a possibility its coming from window.
Next step is to get in there and close boot with a powerful torch and see if there is any light escaping and then after that it will have to be someone in the boot with a torch and me outside with a hose/jet-wash. I cant see how it can get through the boot seal as the seal is raised but I did jet-wash the car the other day so if the seal is bad then that would let a fair amount of water in. Very strange.
None of the water smelled bad either suggesting that all this is a recent thing. I don't remember anything this bad before.
Anyone seen water ingress this bad before or have any ideas other than window seal? It seemed far too much water for it to be the window seal.