Freelander 1 creak noise under front wheel arch

I found a noise coming from the front nearside wheel arch area, more like a creak than a squeak, which is only apparent on rough or uneven road surfaces. I don't think it is suspension or other mechanical component, since it cannot be replicated by bouncing down on the wing or rocking the car. As you are probably aware, the wheel arches have plastic/rubber external shrouds that extend into and around the front of the arch. It sounds to me as if it could be these rubbing against each other when the car oscillates with the road surface. I have had a good look round underneath and there seems to be a number of potential friction points where the various section overlap or are fixed together, but of course I have not been able to produce the noise with the vehicle stationary. The vehicle is in exceptional general condition, but this noise is driving me to distraction. Is this a common problem on the Freelander and do you have any suggestions about where to look and how to locate and rectify the fault?

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