Moynihan, John (Seán) Power (1892–1964), secretary to the executive council and assistant secretary of the Department of Finance, was born 19 January 1892 in Cork city, second child and second son of Maurice Moynihan (1864–1918) and Mary Moynihan (née Power), and had four younger brothers (one of whom was Maurice Moynihan (qv) 1902–99) and a sister. The Moynihans and the Powers were prominent Kerry Fenians (IRB) who had been active in the land war. His father was working in Cork as a butter agent but moved back to Tralee shortly after John's birth and the family remained there until the mid 1920s.
There was less than a year in age between John and his eldest brother Michael, to whom he was particularly close. Both brothers were very well read, and after Michael's departure for university in 1908 and later for employment in the British civil service, their correspondence testified to the encyclopedic range of their interests and activities over the following decade. The correspondence was also revealing of their different personalities: Michael was brilliant and restless, John was more deliberate and patient. He went into the family butter business and when his father contracted tuberculosis in 1913, John provided much needed support to his mother and siblings.
In his letters to Michael as the third home rule bill was going through parliament in 1912–13, John's political views were those of a moderate home ruler. He had also joined the Tralee branch of the Gaelic League but a turning point occurred after the 1916 rising. His father was still closely involved with the Tralee IRB and knew about the plans for a rising in Kerry, which collapsed after a series of mishaps. John wrote a long letter to Michael, who had joined the British army and was about to depart for France, describing the failure of the rising and its aftermath. The letter, an important contemporary source, graphically illustrated the change of opinion that was already sweeping the country following the executions and the mass arrests.
Despite a serious illness in autumn 1916, John joined B Company of the Tralee Volunteers in July 1917 but resigned the following year as he was becoming more active in Sinn Féin. He was also thinking of entering the priesthood but in 1918 the deaths, within six months of each other, of his father and Michael made that impossible. He was now the mainstay of the family, the youngest of whom was only five years old. He became a Sinn Féin member of Kerry county council and of Tralee urban district council. He was also chairman of the Sinn Féin courts in Tralee. In 1922 he became editor of the Kerry Leader, which was suppressed after the outbreak of the civil war. When Free State forces arrived in Tralee, John was arrested in August 1922 and interned until the end of 1923. His sister Hannah was also interned.
After he was released he was appointed editor of the Kerry Reporter and the Kerry News but they ceased publication in 1926. By this time the rest of the family had moved to Dublin, where his brothers Maurice and Denis were working in the Free State civil service. In 1927 he was appointed director of information for the new Fianna Fáil party and worked on the party newspaper, The Nation. He also wrote a number of policy papers, including Agricultural credit (1928). He became increasingly close to Éamon de Valera (qv) and in 1929–30 accompanied him to the US when de Valera was setting up the Irish Press. John briefly worked as leader writer and assistant editor on the new paper from September 1931 to March 1932, when Fianna Fáil came to power. De Valera appointed him secretary to the executive council, a position he held until 1937, when he was succeeded by his brother. Maurice had been de Valera's private secretary in 1932 and returned to the president's department in 1936 to work on the drafting of the new constitution. While secretary to the executive council, John was a member of the Irish delegation to the imperial economic conference in Ottawa in July–August 1932. He was also a member of the commission on banking, currency and credit which reported in 1938. (In official documents he used the Irish form of his surname, Seán Ó Muimhneacháin.)
John moved to the Department of Finance, where he was appointed assistant secretary in charge of establishments. He was actively involved in the Legion of Mary and in two ecumenical groups, the Pillar of Fire Society and the Mercier Society, which disbanded after expressions of disapproval from the catholic archbishop of Dublin, John Charles McQuaid (qv). In June 1952 Moynihan took early retirement from the civil service. The secretary of the Department of Finance, James McElligott (qv), wrote that ‘there was no name more respected in the whole civil service than your own and you earned your laurels in the most difficult job of the whole administration’. Moynihan remained very close to de Valera and spent the rest of 1952 with him when the taoiseach was undergoing lengthy eye treatment in the Netherlands.
After the death of his mother in 1949 he lived briefly with his brother Maurice and his family. In 1955 he went to Glasgow to live with his widowed sister Hannah and was active there in the Legion of Mary. He died in Glasgow on 10 December 1964 and was buried near his mother in Clontarf cemetery.