think I've found the problem!
The drivers side (LHD) shock is rattling on the lower shock mount bolt...hence when you go over little ridges in the road it rattles inside the shock lower hole. It looks to me as though it may have been fitted incorrectly as there is no washer etc...had new shocks about 12 months ago and the garage shall remain nameless for now. Going to get these check out tomorrow so I will let you know the score...
Anyone had this before?