2010 E70 X5 - Squeaking Noise from rear of car

[Sm[]key]

My car has been suffering from a ‘squeaking’ noise when travelling and is noticeable when a low speeds with windows open.

I assumed it was my rear heat shields under the boot moving, I removed these however the squeaking is still there.

I jacked the rear up and took the wheels off, and used a long bar to replicate movement when driving but nothing seen.

Any ideas what the issue could be?

[Greydog]

Rear rose bushes with the suspension inflated nothing moves try standing on the sill and rocking the car side to side
The next symptom will be increased camber and inner tyre wear