Well my condensation patch is back again, but this time the boot is 99% dry.
I washed the car yesterday but stupidly didn't check for the condensation before I started, but noticed it when I'd finished. It could have been there before I started washing for all I know.
There was a very small damp patch under the boot floor in the right hand corner nearest the rear by the box the jack is in. This to me is smacking of water coming in around the light clusters as you said Paul. I will have to get them out to check. Is there a gasket or seal on the back of the lights where they mate with the bodywork?
I'm still not sure about the condensation though. I'm beginning to think there may well be a pin hole in the rear glass seal or something. Baaah !!!!