Hi Stuart,
Wow, you have good data. It is early here in Ireland, and I am supposed to be finishing my PhD, but instead I'm doing something much more interesting. I have very similar information about the Howells of Rath/Clonmore as you do, but I can trace (with evidence) only to 1859. I know it is very likely that any Richard Howell in the area is probably a relation, it is a small rural area, and the name is too particular to be a coincidence. My father's uncles (now in their 80s) have names like Richard, William & Patrick too. Howell in general though, although not particularly common, is not especially rare, there are many Howell families in Cork and elsewhere (a few hundred miles away from Clonmore) so I'm concentrating on the Clonmore/Louth ones. The fact that Mary Anne married a Protestant from another county (she would have been a Protestant too) suggests an arranged marriage. This was the norm for the time, especially in land owning Protestant families, or so I'm told. It might have been difficult for them to meet someone from that far away in those days, unless some element of planning was involved! I will try the Louth library's collection of Historical Journals, these are not online and so may yield something. I will also head to the National Archives in a few weeks to continue digging. If I could connect the Catholic Richard Howell to the Protestant Richard Howell it would be a major breakthrough for me.
Regards,
Stephen