About James Macmahon
Lived 1865 – 1954 (aged 89). James Macmahon was a British and Irish businessperson.
James Macmahon PC (Ire) (20 April 1865 – 1 May 1954) was an Irish civil servant and businessman.
Macmahon was born in Belfast and raised as a Roman Catholic. He was educated at St Patrick's College, Armagh and Blackrock College in Dublin. He joined the Irish Post Office, being promoted to Assistant Secretary in 1913 and Secretary in 1916. In 1918, he became Under-Secretary for Ireland.
There was a need to decode the coded messages sent to the Dublin Castle administration from London. Macmahon appointed GPO worker Nancy O'Brien due to her dedication and purported lack of interest in politics. However, O'Brien was a second cousin of Michael Collins, and each day, between 2:30 and 3:30, she would pass any salient information she acquired to either Joe McGrath, Liam Tobin or Desmond FitzGerald.
Macmahon was appointed to the Privy Council of Ireland in the 1920 New Year Honours, entitling him to the style "The Right Honourable". He remained Under-Secretary until his retirement on the formation of the Irish Free State in 1922. He went into business in Dublin. In 1947, he was elected president of the Royal Dublin Society. He died on 1 May 1954, aged 89.
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Important facts
People in James Macmahon's life
Named in this biography and alive at the same time
Contemporaries
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Frequently asked questions
Who was James Macmahon?
Irish civil servant and businessman (1865–1954)
When was James Macmahon born?
James Macmahon was born on 20 April 1865 in Belfast.
When did James Macmahon die?
James Macmahon died on 1 May 1954.
What was James Macmahon's occupation?
James Macmahon was a businessperson.
What nationality was James Macmahon?
James Macmahon was British and Irish.
Sources & further reading
Cite this page
APA: Biography.guide. (2026). James Macmahon. https://biography.guide/james-macmahon/
MLA: "James Macmahon." Biography.guide, https://biography.guide/james-macmahon/.
Chicago: "James Macmahon." Biography.guide. https://biography.guide/james-macmahon/.
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