D2 Rear Passenger Footwell Wet

[Nognar]

Ladies and Gents,

This subject has been done to death and there are many excellent threads and stickies on this subject but alas my A8 is still moist.

I have a damp rear passenger side footwell carpet in the back of the car, specifically the rear corner of it closest to the door.

To cover off what I have done so far and the symptoms:

1) All other footwell carpets are dry its just the rear part of the rear passenger footwell
2) The Evaporator drains have been checked, both are clear and work as expected
3) The front cowl drain has been checked by the bulkhead and is also clear and working
4) Botangs hole has been repaired, sealed and is not leaking
5) The sunroof drains have also been checked, again clear and working as expected
6) I have also checked the rear heater vents and again clear and nothing coming out of those from the centre or under the seats
7) The boot is also dry and nothing in that area is wet
8) The water ingress is from rain and happened last when the car was stationary over night

As you can see I have checked most of the standard areas that the D2 can get leaks from.

My current thought is its actually coming in through the rear passenger door somehow, has anyone had anything similar that caused a wet patch?

I have been through the car this weekend and last weekend to see if I can work it out and to date its got me scratching my head.

Though on a more positive note I did repair a faulty EGR Valve on my A2

Any thoughts?