So I left the car parked up all winter under cover and since its been out the last couple of weeks with some rain there was again water in the foam of the rear footwell.
It turns out that this hole to the right side of the ECU box under the air con pipes was leaking in water. It was coming in to the passenger footwell and then traveling to the rear in a recess that I had missed before when I checked for moisture in the front.
Since I plugged the hole with a bolt and plenty of sealant its dry!
Thanks for all the pointers, I would never have found that with out the references.
Will get the car ready to sell it now as the D3 just arrived
