Junk in the trunk? A big box full of stuff you don't really need.

Literally yes.  Or a fat ass on a woman. 

OM/G/!!! The water is coming out somewhere /else/ now. Less than before so we're obviously doing something right. All in the back left corner of the boot. Grrrrrrr.

Right. Well, I removed the light cluster, tried to find a leaky spot. No luck. Put the light back in so I could spray the car with more water and... nothing. Not a drop and loads of water on it. I really really really hope that may be it for the boot.

However, there is also water in the front passenger foot well which, from the link posted about, is probably the pollen filter leaking. Another thing to fix.

If it keeps up seal the trunk up real good and buy some fish and turtles. 

Haha. I think that might be a good idea. Turn it onto a fish tank/pond.

I'm still waiting for some proper rainy time but there have been a couple of days of heavy rain this week and we seem to only have about a tea spoon of water in the boot now. Much better than the pond we used to have. No horrible damp smell in there now either.