I wish you luck, The grave was very overgrown when we visited in 1996 The church warden does have a book of records of the grave sights. So your father would be advised to seek help from the warden as we were first sent to Gloucester Records Office and they had no records.
Interestingly We are linked to the Harris family I wonder if their is any conection to your person. Please write of line tarbart AT tadaust.org.au