Hi Everyone,
Just reporting back on my cure for rear "rattling noise" in case it helps anyone else diagnose the problem.
Rattle (banging) noise came from rear drivers side whenever i drove over rough ground or speed bumps but only at speeds up to 20mph. The noise never occurred when driving faster than this.
The only exception was when I drove over cats eyes on the motorway, then the sound would occur.
Turns out it was the rear trailing arm. Part cost £60 new from ebay, £30 to fit.
In the end I now have the sweet sound of the flat 6 to listen to and no rattles :-)
Hope this helps someone. It took me ages to diagnose the problem.
Cheers