Hope I have read all the detail in your post correctly and that these bits help get you started. Let me know if you need any more.
Pontypool, Monmouthshire
WELSH, James, Q2/1886 11A/147* see below
WELSH, Johanna Q3/1889 11A/128 (No trace of marriage to Banks)
WELSH, Thomas Q3/1891 11A/149 (No trace of a marriage to Alice Powell)
WELSH, William Q1/1895 11A/162 (Welch William Died Q1/1932 11A/353)
Bedwellty, Monmouthshire
The only WELCH, William born Q1/1893 11A/58 died there age 1
*1911 James maybe
2nd Battalion: The Royal Irish Regiment, 2ND BATTALION ROYAL IRISH REGIMENT, FORT GEORGE, GUERNSEY, CHANNEL ISLANDS
Regards
Colin