He was the son of John Mason and Jane Barbara Mason. In 1901 the family were living in house 2, Main Street, Boyle, Co. Roscommon.
In 1911 Mason is boarding in house 9, Doonan, Donegal, Co. Donegal. He is described as a Bank Official. A possible colleague, George Albert Barnes (Bank Official) also boards in this house.
The Belfast Banking Company 'Roll of Honour' booklet records Mason as having been 'previously wounded' with his last known address as 'Salonika'.