Well a few days of rain and just washed the car with a pressure washer. Looks good to me now. No more water pouring in anywhere, but here's a funny thing.
Car had been sat outside all day in the sun. Snow-foamed the car and then rinsed off with pressure washer. Obviously the water coming out of pressure washer is stone cold, but after the rinse, the whole front windscreen is steamed up inside. Completely white with condensation. No other glass in car was like this. The rest of the glazing was clear and dry.
Now is it possible I have a leak in the windscreen seal as well? Or could it be moist air getting in through the vents? Blocked drains somewhere (I don't have a sunroof). I'd have thought with ALL leaks sealed up the air inside the car should be bone dry now as I always have the AC on. Why only the front screen too?