Have you a roof antenna?
If it is definitely the windscreen, how much might it cost to get it taken out, cleaned out, and reseated??Cheers guys
screen is bonded in so its not easy to take out,its more likely to be ingress via the roof rails as you have disturbed them
as for the fire wall one - I found a leak coming in around the foam bung that seals the heater box as it goes through.I tried sealing it from inside, but did not stop (I had pressure sprayer spraying to find out where leak was around screen, down inside engine bay etc) - in the end I used some expanding foam inside engine bay - got it down there by using some 15mm pipe as a nozzle extension. Thats stopped that one, but that was not only one.