So the loud clonk (see HERE ) has been located.
I took off the wheels and removed the rear trailing arms. At first the arms looked ok, whilst the rubbers show signs of wear they are certainly not worn out. However a glance back at the mounting point showed the real source of the problem....
The mounting bracket has oval shaped holes worn in it. This permits the axle to rotate about its own axis and results in a loud clonk as the clutch is released.
The bracket is worn the same on both flanges. Therefore I have got to work out a fix for it.
The bracket on the other side of the car is not worn and shows how it should look....
The rubbers themselves are showing signs of wear with small splits appearing at the edges....
The rubbers are very expensive but as I have taken it apart I might as well sort everything out in one go. The rubbers are on order and I am looking at ways to repair the oval hole.