Following on from having my lower arms replaced I had the car popped on a 4-wheel alignment rig to check everything was good. In what was described as "shocking" even the rear toe adjustment bolts moved. 

However, as can be seen in the pic the rear camber is getting a bit close to the edge of what's acceptable. Can anyone tell me which arm/bush/link controls the rear camber? I assume its not adjustable and I'd have to replace said part on both sides to bring everything back towards the centre?

A bit of camber on the rear is normal on these, it helps to keep the keep the car planted through fast corners. Those measurements are absolutely fine, I wouldn't change anything.

It's set by the rear arms but will change slightly when the toe adjustment bolts are moved.  It's a compromise between the toe and camber on the rear hence the wide tolerance.

Thanks for the confirmation. The car seems a bit better with its non-knackered front arms and correct rear toe!