The radiocarbon dating was done on the mortar.
http://www.ramtops.co.uk/newport.html
And the invoices for the construction of the Chesterton Windmill as a windmill were found about 20 years ago.
Doug
Interesting...Thanks for the link. I imagine that had the British not damaged a good amount of the top of the tower - which I have read referenced to - the investigation would have yielded more concrete results sooner.
I wonder why they did not test the clay pipe fragment they found. First I heard of that.