Water Leak- Passenger Floor-Not AC problem

[Sharklet]

Hi - would appreciate any thoughts on this.
Have an 05 1.3 Petrol VVT RHD in the UK (so AC not needed so do not think it is a clogged drain!)
The Passenger floor is soaking - have checked that water drains from the windscreen ok (original screen). Floor Seals are in place and cannot see any leaks from Door/Passenger Window.

Have removed Glovebox and Carpets as far as possible (how difficult are the carpets to get out!) and run a water hose down the screen and after a few minutes can see water trickling down the angled panel forward of the passenger floor about 3-4 inches from the tunnel.

Have read somewhere that the AC/Pollen filter housing seal can deteriorate - any ideas how easy this is to get to and would this cause this?

Or any other ideas appreciated.

Thanks