Gay, Thomas Earnan (1884–1953), librarian and republican, was born in Dublin on 22 January 1884, the eldest of six children (two girls and four boys) of Thomas Patrick Gay, a porter and later a warehouseman, and his wife Catherine (née Coleman). He was educated at the CBS, Synge Street, Dublin, and took examinations of the Library Association (UK) in classification and library routine. In 1900 he was appointed third-class officer with Dublin Corporation libraries, serving in Charleville Mall. He moved to Thomas Street in 1904 and in 1915 was appointed librarian in Capel Street library. A prominent member of the library profession and an active member of the Library Association of Ireland (LAI) (founded 1928), he was elected chair of the first executive board of the association and remained involved in the LAI throughout his career. He was also an active trade unionist and member of the Irish Local Government Officials Union (ILGOU), representing the Dublin library service on its executive committee, and was elected as honorary president of the ILGOU in June 1927.
In September 1914 Gay joined the Irish Volunteers as a member of A Company, 4th Dublin battalion. On hearing of the rising he reported for duty on Easter Monday 1916 to Captain Con Colbert (qv) at the Watkin's brewery/Marrowbone Lane distillery garrison. Colbert informed Gay that he had enough men inside and assigned him to supply duties and maintaining communications with other garrisons. He was also charged with intelligence duties: as the librarian in Capel Street, he knew the area well and, avoiding arrest, became the eyes and ears of the company. His external liaison duties allowed him acquire information about the movement of a detachment of Sherwood Foresters which forewarned the Volunteers at Marrowbone Lane of a planned offensive. Acting under Colbert's instructions to bring food supplies from the Jacob's factory garrison to Marrowbone Lane, he was in Jacob's as news arrived of the surrender at the GPO. Gay carried the verbal order of surrender from Major John MacBride (qv) to Seamus Murphy who was acting for Colbert at the distillery, but was sent back to Jacob's to request the order in writing.
After the rising, Gay eluded arrest, and was able to assist his comrades in prison in England by contributing to the Volunteer Dependants' Fund. He continued to put himself in danger by providing accommodation in his home to his future brother-in-law, Jack O'Shaughnessy, who was wounded while serving with the Volunteers in the South Dublin Union. In the aftermath of the rising, Gay was contacted by Joe Kavanagh, a detective officer in Dublin Castle with whom he subsequently maintained contact., During 1918–21, Gay's career is noteworthy for his work as an intelligence officer on the GHQ staff of the Volunteers, reporting directly to Michael Collins (qv). Contemporary reports indicate that Collins was a regular visitor to Gay's home at 8 Haddon Road, Clontarf, and his revelation there of a secret RIC file showed the trust he placed in Gay. Eamon Broy (qv), an IRA intelligence agent (1917–21), recorded that his main liaison with Collins was through Gay. Broy regularly used Gay's home and the municipal library in Capel Street for contact with Collins. Gay acted as a liaison officer between the IRA and the RIC and DMP, Piaras Béaslaí (qv) recording the existence of a system of communication through which Gay passed information to Collins from detectives Joe Kavanagh and James McNamara. Gay is credited with providing the information which in May 1918 gave prior warning of the 'German plot' arrests which enabled Collins, Harry Boland (qv) and others to escape a round-up of senior republicans. From 1918 until the 1921 truce, Gay's network was critical to Collins's undermining of British intelligence by building an efficient system of counter-intelligence.
Sport and culture influenced Gay in becoming an unlikely intelligence officer. Allied to his work as a librarian, these led him into meeting a diverse network of nationalist cultural idealists and revolutionaries in the early 1900s. He was a member of Cumann na Leabharlann (founded 1904, dissolved 1909), a forerunner to the Library Association of Ireland founded in 1928, and of the Gaelic League and the GAA; his club Croke's provided a base for recruitment into the Irish Volunteers, and some thirty-two of its forty members were involved in the 1916 rising. He also supported the game of camogie, being founder of the Dublin Camogie League and its honorary secretary for some years.
In 1922 Gay was commissioned captain in the Free State army and assigned to intelligence duties. In June 1923 he was promoted to colonel, and attached to the chief-of-staff's department. He resigned from the national forces on 20 December 1923 and returned to Dublin Corporation to work in Capel Street library. In 1939, during the Emergency, he was appointed air-raid precautions officer with Dublin Corporation. Subsequently he worked as private secretary to the Dublin city manager and in general administration in the corporation until he retired in late 1947. He was later secretary of the 1916–21 Club which sought to bring former comrades together after the civil war, and a leading member of its pensions committee.
In September 1917 he married Eileen O'Shaughnessy, a milliner, of Grand Canal Bank, Rialto, Dublin. She was a member of Cumann na mBan and was involved in the Howth gun-running of July 1914. They had three children, Kevin, Mary and Eileen. Kevin (1922–2000) was called to the bar in 1956 and became probate officer of the high and supreme courts (1980–85). When his wife died in 1924, Gay moved to 11 Sandford Avenue and later to 15 Grantham Street, both off Dublin's South Circular Road. He died in Dublin on 2 January 1953. After a military funeral, attended by many former IRA and national army comrades, he was buried in Glasnevin cemetery.