Hi Red Rags
Welcome to the forum,
I think I have to agree with SWB regarding the studio photograph, the uniform certainly looks and fits ok. The ammunition bandolier and Mauser rifle could have been studio props, and the hat doesn't seem to match his well worn uniform and looks very much like a S A C example. The collar badges are intriguing, they look like seperated buttons at first glance. However, the image angle could have played tricks and they may well be Fusilier pips. I thought Inniskilling to begin with, but no P Fagan, P Fegan that I could find pertaining to that regiment. Although I did find a J Fagan 1st Battalion Inniskilling Fusiliers. The following names have the correct initial which may be beneficial.
P Fagan 7205 2nd Battalion Royal Irish Fusiliers
P Fagan 5484 1st Battalion Royal Irish Fusiliers
P Fagan 1810 Royal Irish Rifles.
4593 P Fagan you have already dismissed.
Of course we are assuming that P Fegan, Fagen served in an Irish regiment!
You mentioned the family are adamant he was born in Armagh in 1870? Is it possible that you could provide more details regarding his family? For example was his mother called Letitia? Could his father have been Hugo? His trade or calling if known. I found Fegan's in Armagh who were farmers for example.
I find the more clues and details provided may help with the research. Is it possible P Fagan, Fegan, Feighan could have travelled to South Africa before hostilities began? The more details you can share, if they exist of course, the better chance of solving the enigma.
I have attached a few images for uniform comparison and insignia.
These include, Inniskilling, Dublin Fusiliers
Plus the Ancestry roll pertaining to Fagan / Fegan, South Africa.
Note number 8 on the regiments list is an Ancestry error.
Dave
Inniskilling Fusiliers 1897/98
Dublin Fusiliers