Wet inside rear quarter panel & rear floor smells musty (right hand side only)

I noticed the smell on the rear floor pan carpet first. So I replaced the roof aerial seal, as that was old and brittle, but it doesn't appear to have let any water in. So I had a look around and noticed the rear quarter panel was wet, but it was condensation that had settled on the inside of the panel, so it hasnt helped locate the leak. I took the rear light off and the foam seal looked intact. I'm gonna prod the drain in the fuel neck to make sure that isn't blocked. And I'll check the rear wash pipe hasn't popped off.
Any other ideas?

 

So off side ?
Had problems with broken rear washer pipe on one of my old mans golfs but that was near side iirc

Borrow a dehumidifier or get some cat litter silica crystals in a tray in the boot to dry it out after getting what you can out by hover or clothes

 

Check if your sill drains are not clogged.

 

Yes offside.
I have just bought some silicone too.
I'll look into sill drains
Ta

 

Take a look inside the arch and give it a good inspection too. Up around the turret area or for possible holes to the quarter side.

 

Dogging residue?

 

No sunroof.
Smells like a ferret had died in there, so could be an old festering dogging related splurge