Leaking water by interior mirror

[Balleruk]

My father has just bought a 2007 520d touring, and has noticed water leaking into the cabin around the interior mirror. We have checked the seal around the top of the windscreen, which seems fine.

Would the tube to the rear washer jets run up an a pillar, and down the centre of the roof (unlikely i know, but I cant think of anything else it could be!)

Thanks for reading.