Hi there - these diagrams helped me find my problem so thanks very much. My issue was with the rear drainage on the sunroof which was causing water to drip down the rear pillar and into the rear passenger footwell (especially when the car was facing uphill!)
I had to locate the bottom of the pipe which is behind the rear wheel arch and I discovered it had a kink in it stopping the water. Released the kink and boom! all gone. Bit of tape to reinforce the wall and stop it happening again and hopefully all sorted. Getting to the bottom hose here pretty easy...
Images attached!
