[Nognar]

Removed the door panel today and indeed it was wet inside.

The foam sound deadening material was soaked at the bottom behind the speaker. Clearly water had been getting in and dripping down to the bottom and causing the wet carpets.

Interestingly though I was expecting a membrane or some clear plastic as part of the door to keep the water out but there was nothing! Maybe someone has been there before and not put it back which would explain a lot!

Therefore I have used some clear plastic sheeting to keep the window mechanism part separated from the foam insulation part with the hope that stops the water getting into the footwell.

Poured water to test and it drains out the bottom of the door as expected, nothing blocked so it may be the the angle the car is parked. Hence I hope the plastic sheet shall be enough to keep the water dripping out the bottom and not getting onto the foam.