Heavy Condensation on Windows

[The Monzta]

Now the weather has changed for the worse and the temperature plummeted I notice I'm getting a lot of condensation on the interior of my glass......moderately bad on the windscreen sometimes, pretty bad most of the time on the rear screen. Condensation usually means water ingress from somewhere so this evening when I got home from work I had a look round for the culprit.

As the rear windows are signficantly worse than the front I started searching the rear. The carpets were dry, under the rear seat was too, the spare wheel well and under the luggage area carpet also bone dry. I then opened the folding box to the left (where the CD-changer usually goes) and peered down into the left side rear wing cavity with a torch. And down at the bottom there was a puddle of water about an inch and a half deep. Gotcha!!!

Now then, where's the water most likely to be coming from, is it a common problem and is the right hand side prone to this also? I've heard that the radio aerial's are prone to letting in water......is this correct?