Steve, I have a similar issue on the bonnet and around the top of the wings of my red 4/4. I wondered if it was connected to the autoglym hi def wax I used - as the first circles appeared after I treated it to some a year or so ago.
Last year I had the car detailed which improved it a lot, but the chap who did it was reticent to get too aggressive with the cutting compound on 24 year old paint.
I think I need to let him have another go, I had been wondering about clay, as I was able to restore the blackness back to our jeep last summer
