2001 Jaguar Sovereign Strange Noise!!

Hi there,

Just bought a V8 Sovereign 2001. Driving it cold for a few miles is perfect, but after about ten miles or so once it has warmed up a bit there is a noise only when idleing (not when the car is in motion) a bit like someone is ratteling a chain under the bonnet. Does anyone have any ideas, or even know anyone in East London or Essex who might be able to solve the problem???

Thanks vey much guys!!