Thanks for that link, i was unaware of the dangers of Gunk. I notice the last post mentioned the citrus degreaser, i wonder would it have the same potential for causing damage?
It seems to be a balance between using the spray degreaser and cleaning shortly afterwards or using something milder than Gunk for a longer soak.
I should add, i used the spray degreaser on the freewheel and then washed it out with water. I then oiled it with light oil using a precision oiler (thanks Ian). I removed a lot of old oily muck from inside the freewheel, perhaps this was keeping it quiet and albelit it was 'oily muck' is was still oil which would provide lubrication and protection to some extent.
Thanks again!