Sgt McMurrough of Leinster Regt was alleged to have been the first volunteer, but withdrew when he heard that there was no money in it for him. Quinlisk reords this hapening during Casements first address to the NCOs at Limburg on 6 Dec 1914.
1883 Casements diary puts his birth at about this date, which ties in with enlisting at the age of 20
The closest birth in Belfast appears to be John James McMurrough in 1887 in IFHF database, and same chap in Irish GRO
1903 autumn. From his service number, he enlisted around this date.
1911 Census in Francis McMurrough, a Corporal with 2nd Battalion The Leinster Regiment, at Jullundur, Punjab, IndiaJ. Single, Age 28 Born 1883 in Belfast
Casement makes references to him giving his age as 32
I left two exercise books with Sergeant MacMurrough of the Leinsters and with Timothy Quinlisk of the 18th to fill up with names of all men and regiments. These two are keen for the Brigade – so they say. Mac M is a dark-eyed, black bearded Sergeant of the Leinsters from Belfast originally & once a postal clerk! He admitted his enlistment was due to “financial trouble”!* [Footnote:] *I expect it was! & that he would not return to Ireland “with a red coat.”