Still no news on this?
I had my dad drive mine today while I sat in the back and had a good snoop around, putting seats down etc, sounds to me like the rattle coming from high up in the boot area. I left the parcel shelf in as I know its not that but I had the boot floor out (I know its not the floor but just wanted it out in case it was something below it).
When I had my head in the boot (below the shelf) the sound couldn't be heard, I could only hear it when I was higher above the parcel shelf, so the noise for me at least is focused very high up in the back of the car and behind the rear seats for sure.
It can surely only be the actual top of the boot door itself, or possibly the stantions (don't know their correct name sorry) that enable the boot door to stay up when u open it. There is a little play in them from side to side if I try to wiggle them. Thinking maybe some insulating foam around them is my next step.
Unless im just crazy as no one else can seem to hear it, but its the most obvious noise to me now that my ears are acutely tuned into its irritating sound lol