Thanks Pete,
Light bulb moment on the "Cones", Now I know what's being talked about, the cones I replaced about six months ago to poly ones as the bonnet was not sitting correctly aligned. Its probably not this then as the noise was there before and after the change - but I will have a play bouncing on the bonnet to see if I can replicate the sound. As BEn says though, another pair of ears from the club may well be the route to finding the source
I will take a look at the bush, If I remove the top centre bolt can I replace from there if I jack up the car or do I need to strip the suspension down? I was going to do this in nthe winter as my next project as allthe bushes are pretty old in the front suspension - possibly original or at least from the 1980's!
Aidan