Here are a couple of civil registration records for you to consider...
Firstly, the death registered in Londonderry in February 1919 of a widowed Hugh Lynch with a reported age of 55 and occupation of 'Potatoe Hawker', the informant was his son Daniel Lynch, in particular, note the address of death -
17 Donegal Place:
https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_returns/deaths_1919/05161/4423259.pdfSecondly, the marriage registered in Londonderry under a year later in January 1920 of a Hugh Lynch to Sarah Quigley, the groom's father stated as Hugh Lynch
a butcher - note the groom's address:-
17 Donegal Place Derry:
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1920/09259/5351967.pdfDathai's 1911 census potato dealer is looking like the same man as the 1901 butcher and cattle dealer. If so, (notwithstanding that the 1911 census age may have been inflated due to the introduction of the Old Age Pension), then Hugh's age is simply all over the place.
In a roundabout way the point I'm making is that, in the circumstances, you might want to seriously consider the following baptism for a Hugh Lynch baptised in All Saints RC parish on 27 March
1853, parents given as John Lynch and Margaret Harkin (top of next page):
https://registers.nli.ie/registers/vtls000631911#page/32/mode/1up Added: I can also see a marriage in Londonderry for a Daniel Lynch and Elizabeth O'Donnell in 1922, the groom's father given as Hugh Lynch a butcher, the groom's address as... 17 Donegal Place.