OK totaly confused now, got home from work and the weather has cleared up here so left it intil about an hour and half ago, before I took it apart again I thought I would give it a good soaking, so ran the hose on low over the windscreen, in the corner, into the gaps in the sills, door slats, even put the hose head down inside the corner of the screen so that full water flow was going into the corner where the drain hole is and then ran it all along the vents at the bottom of the windscreen and no water came in, so left it running for a while and still no leak??? so parked it on the drive so it was sloping uphill and downhill and soaked it again and still no leak. Did the same as above but with the hose on full and again no water came in.
So attached the hose to the Karcher Pressure washer and again blasted it all over the windscreen causing a flood to come down as I did with the hose, fired it into the gaps between the sills and close range all along the bottom of the windscreen and plastic bulkhead cover, still no trickle of water??? next thing I did was actually stcik the hose head into the corner hole with the bonnet shut and turn the hose on full power, this literally flooded the bulkhead in the corner and water was flooding out underneath the car and through the drain holes, but still no water coming in???
Then one last try I attached the jet wash again and put the end of the jetwash in the corner of the bonnet at point blank range and fired it for ages again flooding the corner and did this all along the bulkhead plastic cover filling it at quite a rate and still no water leaking in, so looks like the leak has gone?
Thing is after taking out the pollen filter cover, seal, filter and putting them all back in again (twice) earlier today a trickle of water still came in after I wiped the area in the pic dry and they fired my windscreen washers constantly for about 40 seconds, I then waited and after 10 seconds the water trickled in.
Only things I can think of is that the drain hole was blocked and it unblocked on the drive home (was dry the whole journey) as I had a leak like this on my S3 drivers side, but the drain hole and whole corner was full of leaves so 100% blocked, it didn't look like the drain hole was blocked on the Leon at all but might have been?
Only time will tell I guess, not gonna cancel the booking with Seat unless it pours with rain all weekend and no sign of a leak (might even run it through a car wash just to give it one last soaking) if it still does not leak I am off on Monday anyway so may just let them have it in the afternoon and see if they can water test it and make it leak.