Sue, I am absolutely positive that the Robert Corkill b.1844 is correct. He traveled to America in 1866 with his wife Jane Kennish whom he married in 1865 on IOM. I have Pioneer records from Kewanee Illinois giving detail of where he was born, when, and his children and wife's name. He is the father of my great grandfather born in 1875 in Illinois. I have the census records for that time, etc.
There is no question that he is the one.