Over the last few weeks I have had a small leak coming through behind the passenger rear light. It's been an absolute pain in the arse to try and find the source. There is many place where water can get in after doing alot of research, I have had the rear lights out, rear bumper off, double checked the new rubber boot I had just fitted. I even checked under the gas strut bracket with a borescope to see if that was the cause. In the end I thought well there is only one place to look which is under the trim strip that goes down each side of the roof. I found some miniscule cracking and a split which I have attached. I confirmed the leak by making an end-cap out of blue-tack and filling the end with water and waited. Sure enough after 8 or so minutes it cam through to my relief. I must have spent 10 hours in total looking for this bloody leak. Fixed it all with a good few layers of high quality colour match paint. Will wait a few days and then will restick the trim down.