You don't say how old your grandfather would of been? Without that its difficult to find a place to start.
There are 42 William Irvine's in the 1901www.census.nationalarchives.ie
has civil registrations of births from
1864 to 1950's.
Maguires Bridge is a village in Fermanagh, Northern Ireland built in 1750 by the Maguire family. It is located 8mi. from
Enniskillen and 3 mi. from Lisnaskea
These are the churches in the community, Methodist, Presbyterian, RC St. Mary's, and Christchurch, Church of Ireland.