Thank you for your quick reply! I only know for certain as far as William b. abt. 1760, and would very much like to find his parents, siblings, etc. He married Martha Talbot Feb. 2, 1789 at Brewood, Staffordshire, England and they had 3 children: John (1789) William (1791) and a daughter Frances (1792). I do not know if Frances married or any of her descendants, but I do know of John and William's - a very large family. A DNA project has also been done on this line. We know that William came to Staffordshire from another area in England, but haven't been able to definately connect him to another Cockerill family. The DNA project proved that our line is different from the Lancashire ones who went on to develop the big Steel Mill in Belgium.
You mention the Cotterill name - is this known to be connected to your Cockerill line?
I would be happy to work with you in any way that could assist either of us.
Mary