Thanks Vickie. I was recently in County Waterford. The old Anglican churches of Kilrossanty (where Patrick was the Vicar), Affane (where Mary resided in her widowhood) and Mothel (the parish which includes the townland of Old Grange) are now picturesque ruins in the case of the first two, and completely demolished in the case of Mothel. There are later gravestones as Irish church sites still have interments but none from the 17th century and early 18th century.
Lismore Cathedral had Victorian rebuilding works and "improvements" during the 19th century, so the there is now no indication of any interments (floor slab memorials) in the place in the choir where John Nettles had his family vault.