Hi David,
Whilst agreeing with everything you say, i just want to offer my thoughts. I realise that it is all conjecture and you have dismissed the man in Cheltenham but here we go.
Looking at baptisms:
I can only see one Hugh around that time (there may be others which are not online) March 1859 son of Patrick and Mary.
This fits with the age you give for 1901 census and with the father's name of Patrick. I can see a child Ardle amongst the several children to Patrick and Mary.
Hugh married Catherine Elmore - father Henry, deceased, Fishmonger.
Witness Peter Rice and William (I think) Hagan.
These surnames are all local to the area and are plentiful - this can be seen from others on the same page in fact.
Catherine's mother was Ellen Hagan, I think.
There is a Matthew O'Hagan in Cheltenham in 1911 - indexes show he is born Carlingford.
There is a Matthew Hagan in 1901 in Lislea with a mother Mary.
Mathew O'Hagan is also in Cheltenham in 1891 - an Oyster dealer but I can't see him in 1901.
Baptisms show children born to Matthew and Mary Murphy including Matthew and a William.
There could be other Williams of course and the witness may not be a William.
As I said, it is conjecture but failing other sightings, I still think the 1911 Hugh is worth considering. Ages often vary in records so are not reliable.
With regard to the occupation, my grandfather is generally listed as a farmer in records but he was also a fisherman and a stone mason.
I just wanted you to see my reasoning.
Regards
Heywood