Update. It wasn't the door or window seal because it just happened again. I discovered that the water was entering the car from high up behind the trim that fits to the left of the front passenger's feet. Very difficult to get to from inside the car. We took the wheel arch liner off and found that there is a rubber bung that pushes up into a void inside the wing. Water pours down into the void from the scuttle and muck eventually totaly blocks the drain. Over time, the void fills up and the water over-spills through a hole into the passenger foot well. I bailed around four liters of water out of the rear foot well and am once again drying the soaking carpets, front to back. The photo, 'blockage 4' shows that the driver's side was also almost blocked with grot. The answer is to blow out the void with an air line.