Whilst rolling the rear fender arches on my FD in preparation for fitment of wider wheels, I noticed the tire clearance gap from left to right are quite a bit different. +10mm
The measure from ground to top of wheel arch is equal, so not uneven ride height
The camber of both wheels is equal
The current rear wheels are confired equal offset
The rolling of rear fenders appears equal, one is not 'flared' more than the other

So now I'm concerned maybe the car has had some previous damage ? Or is this just normal inaccurate manufacturing tolerances?
I assume the whole rear subframe has no lateral adjustment option, and only the lower control arms are adjustable for camber, with no adjustment on the upper A arm

Any ideas or helpful comments would be appreciated

 

Mine was the same side to side when I did my wheels and tires that REALLY needed max clearance.

I would look carefully at the rear subframe, upper suspension arms and camber adjusters

If an upper suspension arm is bent so its shorter on one side it would cause negative camber and then the camber could be adjusted back positive with the eccentric on the lower arm making everything on that side shorter.

You didnt pop a bunch of bondo out rolling the rear so, its probably not body work crash damage (unless it was a quality job patching in a whole metal quarterpanel).

If it all looks good you could try loosening the rear subframe and pushing it over the other direction.

 

How long ago was your last alignment to know your wheels are still at equal camber?