I am no expert in anyway, but are you implying in that pic that the axle isn't level?
It may not be possible, but I would be inclined to jack the car up on both sides so it is level, then see how the axle lies, assuming it is not sitting on the chassis.
The axle is level. It’s the body that is on the P. One side of the axle is the right height from the bump stop, the other is on the chassis bump stop, thus I believe forcing the O/S higher.
I could simply be looking at a naff spring, that has not enough oomph to raise the axle.
I think the opposite is true. The off-side spring has
too much oomph and is not allowing the chassis to settle at it's natural ride height.
It looks to me as though the O/S spring has seized solid and is not allowing the chassis to droop at all.
Have you tried getting a heavy mate to bounce each side in turn while you observe the movement.
My guess is that you will get very little movement on the O/S, if any at all.
I'd get Mulfab to send a new spring and start by changing the O/S. ( Get them to double check the new spring first )