A strange leak

The rear carpet is wet (on my 2005 110 SW)
lt's mainly around the rear O/S side facing seat, and l can't see where the water could be coming in. The carpet is also wet on the floor in that corner.
Below the seat and under the carpet is not just damp, it's properly wet with water droplets on the metal.

Anybody had any leaks there and could advise? l've looked around and can't see anything.

This is something new, it's never leaked there before.

It probably won’t be leaking where it’s wet, the water will track to a low point and then gravity does the rest.

In my 90 I had the same damp patch, source was the tub/waist seal failing allowing wind driven rain to track along the capping and then run down inside (by the B Pillar)

It had also at some point been coming in from the side window frame seal and the alpine light seals and joining up at same low point - a Defender waterfall.

Something similar happens to mine. Water accumulates under the matting in the base of the tub. It seems to be coming in between the tub and the window panels at the sides. There's no carpet on the wheel arch covers that the side seats are mounted on, so that dries up pretty quickly when the rain stops, but once it's under the rubber mat on the floor it stays for ages. I'm not sure there's an easy way to solve it other than taking the body apart and re-doing the seals, so I just live with it. When it's dry, I periodically squirt Dinitrol (the thin, runny variety that creeps into cracks) into the offending seam, so as to slow down the steel corrosion. One day I'll take it apart and do it properly, and maybe even invest in some galvanised cappings, but it doesn't seem quite bad enough to merit that at present.