Thomas Gibson was born on 7 July 1909 at Rockbog, Arklow, County Wicklow. He was the son of John Gibson, a sett-maker and stone dresser, and Elizabeth Kavanagh.
His birth was registered on 28 July 1909 by Marcella Doyle of Well Lane, Arklow, who was present at the birth. His father's occupation is listed as Sett-Maker.
Recorded as a 1-year-old grandson living at Rock Big, Arklow, in the household of his paternal grandfather, Peter Gibson. He is enumerated with his parents, John and Elizabeth, and siblings Margaret Mary and Peter.
Enumerated as a 16-year-old single son at House 20, St. Brigid's Terrace, Arklow. His occupation is listed as a "Labourer at Water Works" employed by Messrs Lee Bros Contractors (Builder). The return notes he had been "Out of work for 1 week" at the time of the census.