Again thank you very much for the info.
It seems that I the "John and Catherine" household in Derrymore probably isn't my line - looking at it more closely:
1). John is aged 16 in the Derrymore 1901 census - and in my 1911 census which is definatley our family he is 34 - bit embarresed i hadn't noticed this discrepency before!
2). My 1911 census has John and Elizabeth living in Bunkershill (corresponded by the book clipping) - your find of the "Katherine Moaten as head of family, aged 50 years, widowed, daguther Katherine aged 26 and daughter Bridet, aged 19" on Bunkerhill Street in 1901 is most likely my strand (many thanks for sharing!) - who knows where the 24 year old John is - probably over in England working for the summer - this happened a lot in our family
So it seems that by a quirk, the mystery spouse was a Katherine just not your Catherine! - sadly seems we are not connected to the same Motens. Don't know what to make of the "Letson Moten" question God only knows what is the riddle behind it.
Can I ask where you found the Bunkerhill Street
Katherine Moaten family in 1901 - was it on the http://www.census.nationalarchives.ie
website or have you another document???
Many thanks for all the help and assistance - looks like I'm gonna have to re-write part of my Tree - but no worries anyhow.
Hope you draw the same conclusion - don't know what to do going further back but think i'll focus on the Bunkershill household - try and see how many generations held it going back