Rear axle: on the wonk

[C.A.R.]

Haven't noticed any impact on the handling at all but the rear axle is creaking badly and it's clear that the car is 'wonky'



I have taken what appears to be the worst picture to illustrate this problem, but basically the car leans to the drivers side all the time.

With the symptoms I have described, what is the most likely problem? Buggered shock on the drivers side? Or something worse? The car doesn't seem to have any adverse camber at the rear, hopefully indicating a healthy beam.

If it is the shocks, I'm confident I can replace the myself. But what with? (aftermarket/upgrade?)

Thanks in advance