I went out yesterday after the car had been standing in continuous rain for nearly two days, and to cut a long story short, when I went round a left hand bend a bit sharpish, my right ankle was suddenly dowsed in cold water! When I got home I found the driver's side carpet was sopping wet but how the water got in is a mystery. I took the dashboard skin off but there was no sign of a leak from the screen, which was re-sealed only a year ago, then removed the access panel under the bonnet, but the foam round the aperture was dry and I couldn't feel any wet on the wiper linkage. However, the foam in the bottom of the dashboard structure was saturated, so that was how my ankle got wet.
I'm assuming any water from the lower screen rubber can't find its way down the back of the dashboard, as it must be bonded to the scuttle? It must have been a major leak for that amount of water to get in - when I parked I saw water was trickling from underneath, having escaped through the seat mounting points. I've always had damp carpets in winter, but this is ridiculous...