I am still quite an 'accidental' genealogist. I had looked at pages of Griffiths Valuations before, but they had never made any sense to me. However, armed with "Cullane South" townland and "Ballylanders Parish" from the 1841 census extract for Patrick's older brother James, I decided to look for a map of the area.
Google was again my friend. It led me to a really useful website by John Grenham to look at Ballylanders Parish.
When I clicked on Cullane South, it took me to a Griffiths
Valuations page. Clicking
on occupants led to list of names. John Riordan was there on the second
page. These valuations were done from about 1847 to 1860s or so, so this
would be my great-grandfather Patrick's father John. There is also a "Quain" listed in
Cullane South. There was a number in the left hand column by John Riordan's
name- 20 with an a.
The maps are incredibly useful because there is a slider that lets
you overlay a modern map, and have varying levels of the old/modern
maps. So the Riordan farm lies right on a bend on the modern Cullane/Tully
road- in fact the farm is bisected by it. I reckon I could find it if I went back to Ireland with a car one
day! On the map you could also see that Glenroe/Darragh- where the O'Donnell
priest/cousins came from, was right next to Cullane South.