There is a small plastic panel which I first painted then came the struggle to fit the new lining material onto the old plastic panel, unfortunately this does not look the best of jobs but the plastic that holds the lining material has warped over the years, anyway after a long struggle it was fitted. Next was to refit the switch cluster and finally I put the newly lined rear panel back in and fitted a new washer bottle and motor, the motor is pumping the correct way but no joy in getting the washer to squirt so back to the drawing board on that one, I still came away happy that I had made some progress so the day wasn't wasted.
Jeremy
The answer just has to be a welded repair! 
Yes this was something that I had come across years ago in an old motorcycle rag where bikers were sick of paying out extortionate sums for plastic motorbike fairing bits, so some smarty came up with the idea of welding the plastic together. This is simply accomplished by using a soldering iron to heat up the plastic and using a plastic filler rod; the filler rod was no issue for me as I simply used and old Airfix model kit sprue and so I made my first attempt. 
I will post more photo's once the grill has been filed and repainted, I must say it feels like a much more substantial repair than gluing which does not work.
