My QP (2008 build, an early 2009 S model) had a leaking boot with the first owner, fixed/replaced under warranty. Made quite a mess of the old boot liner as water ends up pooling in the lower storage area (I saw the previous water damaged manuals etc which were in the bottom compartment), but was completely fixed by the dealer before I bought it and has been fine. Apparently it was a faulty rubber seal and I was told not the first they had seen, so it can happen. Have you tried hosing down the boot area and seeing if it gets any worse? That would isolate whether the problem is water coming from outside (i.e. rain etc) or not. Maybe put a towel or something in the boot when you do this and see if any part gets wet? Is the lower area wetter than the upper? Is the car new to you, i.e. is this a newly developed problem on a previously OK car, or are you new to it and it might be a long standing problem?