Clonking noise from front suspension/steering - 2006 Fiesta

Hello there everyone,

If this forum could shed any light on an issue I've been having with my car, I would be extremely grateful! 

My 2006-reg Fiesta (4dr, 1.25l, 78,000 miles) has recently developed an odd clonking/twanging noise, rather like the sound of metal bending or shifting under pressure. This noise is coming from the front of the car, but it's hard to say precisely which side. This noise does not seem to correspond to a particular movement of the steering wheel or a particular kind of road surface (for instance, it does not always sound when going over bumps). However, sometimes it does sound consistently when making small left-right jerks with the wheel as the car moves down the road. This noise has been sounding for just over a week and has got louder in that time. I can feel it through the steering wheel, though this feeling is not itself very noticeable. Once we became aware of it, we replaced both top strut mountings and one of the anti-roll bar struts. Both coil springs have been removed and appear to be in good working order. The noise has not been resolved by any of these measures.

Any ideas?

Simon