Hi Shane,
I'm most grateful to you for your help. It sounds as if Ballinglen was not, as I had imagined, a place where the parents of James Mouls were well dug-in.
As regards his wife's possible preference for Rathdrum as a place she may have been familiar with, that's a likely factor. Her name was Elizabeth Murphy, and so far I've not tried to trace her birth (because of the surname being one that a lot of people shared). Given that Rathdrum is where she got married, she may well have been from there.
It's heartening to know that the Nationa Library has the records for Mucklagh. (Incidentally, I'm aware that in Co.Wicklow there's another Mucklagh, but it's in a more remote location, and I thought the proximity to Ballinglen made the more southerly Mucklagh a better bet.)
Again, many thanks. I greatly appreciate your response.
Best wishes,
Peter