[2] O'Kelly was born in Coramore, on Valentia Island off the County Kerry coast, he was the son of Patrick Kelly, a farmer, and Ellen Sullivan.

The closeness of the contest was due to the strong AOH organisation in the county that campaigned for outgoing North Galway MP Richard Hazleton of the Irish Parliamentary Party.

O'Kelly took his seat in Dáil Éireann as a Sinn Féin TD and was Leas-Cheann Comhairle (deputy chairperson) from 1919 to 1921.

He opposed the Anglo-Irish Treaty that was ratified by the Dáil in January 1922, and refused to accept the legitimacy of the Irish Free State established in December 1922.

He and others maintained that the Irish Republic continued to exist and that the rump of the Second Dáil, composed of those anti-Treaty TDs who had refused to take their seats in what became the Free State parliament, was the only legitimate government for the whole of Ireland.

[10] After the resignation of Éamon de Valera as president of Sinn Féin in 1926, O'Kelly, who maintained an abstentionist policy towards Dáil Éireann, was elected in his place and remained in this position until 1931 when Brian O'Higgins took over the leadership.

This apparently reflected local patriotism (both men came from south-western Ireland near to Sceilg's own birthplace) and Sceilg's own devout Catholicism, which led him to exalt O'Connell's achievement of Catholic Emancipation and Healy's claims that the adultery of Charles Stewart Parnell with Katharine O'Shea made Parnell unfit for political leadership.

[16] In 1930, O'Kelly, speaking as Sinn Féin President to its members, said, "In the signs of the Anti-Christ, England is today the prey of rival groups of unscrupulous Jews fighting for their lands.