When idling in neutral, if I place my foot flat on the floor, I can feel something banging irregularly against the chassis somewhere.
At higher rpm's the noise isn't there (or just can't be heard?).
I've tried looking under the bonnet and I can't isolate the source of the sound, it sounds a bit like a loose fan blade banging a metal part, but my fan is bolted on tightly.
It has increased in severity since last weekend's 370 mile round trip to V-Festival in Staffordshire (which she handled without serious complaint

Has anyone had a problem like this before?
Thanks in advance,
Tom.