I think it must be in the front, but last time it ran back into the rear footwells. This week it was only the front that was wet. We (my old man and I) inspected the pollen filter per Andy's
guide, and discovered a few leaves and stuff but no major blockages etc. However, the black plastic fin that goes over the front of the pollen filter behind the rubber cover had snapped so I will need a replacement one of those, as Superglue doesn't appear to be doing the trick!
Knowing VAG, it'll probably be £20 for a 6-inch long piece of plastic. Part number is 6N2 815 645 if that means anything to anyone?!