Hi Ed
The information about St Paul being a Church of Ireland church is useful; if you look at the 1901/1911 Censuses for Ireland (
http://www.census.nationalarchives.ie/ ) there is this entry:
1901
Residents of a house 12 in St. James Avenue (Mountjoy, Dublin)
Edward J FITZSIMONS
Head
Irish Church
Read & Write
68
Annuitant
Born County Cork
with family:
Elleanora (sic) Wife 60 b County Limerick
Florence Dau 23 b Limerick
Edward J V Son 22 Nil occupation b Galway
Edward John Vize Fitzsimons born 1866 to EJF & Eleanora in Limerick (from the familysearch site) may have died and they named a later son after him.
But at least you now know that this family group were CofI; hopefully it will be easier to identify different Edward Fitzsimons and families if they are Catholic.
KR
Maryam