I've just received a copy of the 1818 baptism entry from Hants Record Office.
In the baptisms of William and Harriet's other three children, the father's occupation is given as "miller".
When they married, Henry Corderoy (1840 & 1850) and Joseph Timbrel Corderoy (1844) gave their father's occupation as "miller".
Henry's baptism at St Mary Bourne describes his father as a "miller"

This now links me into the Corderoys of Blewbury BRK
Many thanks to those who replied . This look-up is now successfully completed.