I tried pre calculating each frame and it helped, I think there are a number of factors that caused the problem and there is no one thing that I can say has solved it.
It either happens or it doesn’t.
As soon as this project is over, they are getting binned.
Believe it or not but, I used the method for a static animation and it worked brilliantly but you have to make the moving objects not visible to GI.
For no good reason all of a sudden these black bits started to appear after numerous successful tests.
The black bits still show when I render still images with their own Irrad and LC solutions so, the method above can’t be the cause. Also, when I render the image at 3000 pixels - the black bits are still there but alot smaller.