Just thought I would share the good news...
Looks like Lexus have found a fix for the Boot Lid/Bumper issue... Car was in for another respray of boot/bumper beginning of Sept, a few days after it came back out I got a call from the dealer to say they had a solution..
The four rubber stops on the boot lid were replaced with slightly longer ones. I have been running the car since then and have paid special attention to the danger area, so far so good, no recurrence of the problem..
So if anyone has any concerns pop down to your dealer and ask for the new rubber stops, easy fix just pull out the old stop and push in the new one.. Happy days :)