I ran across this old thread today!
Elizabeth Arnold who married Charles Houghton, was my second great grand aunt as her sister, Letitia Arnold was my second great grandmother and married Edward Houghton/Haughton of Cloonboygher, Co Leitrim. (Margaret, I think you are the one who introduced me to your cousins as well. One of them has become a dear friend!)
PETER UPTON-DAVIS, I think I can clarify some things for you regarding Charles Edward Houghton/Haughton. Charles was my 1st cousin 4 x removed. You may know this but he was also from Cloonboygher. Cloonboygher is a small townland down the road from Newtowngore. It was not uncommon for them to list Newtowngore or Carrigallen on ship records and other documents rather than their townland. Among his sisters were Isabella and Ellen who both tragically lost their lives in the ship wreck of the Cataraqui on their way to Australia. My grandmother still spoke of the shipwreck when she was alive. This is an old thread, but if you need more info on your Cloonboygher family, I would be happy to share it with you. (Among the family, some spelled it Houghton, some Haughton-but it is all the same family, some times they used both ;-)
You asked if the Houghtons are related to the Arnolds. The short answer is yes but the long answer is yes BUT....they are a confusing story of endogamy that wed in and out of each other's families.