Background
MacDermot was the eldest son of Charles Joseph MacDermot by his wife Arabella Mary, only child of Hyacinth O"Rorke, representative of the House of O"Rorke of Breffny.
MacDermot was the eldest son of Charles Joseph MacDermot by his wife Arabella Mary, only child of Hyacinth O"Rorke, representative of the House of O"Rorke of Breffny.
He succeeded his father 5 September 1873 as The Mac Dermot, Prince of Coolavin.
MacDermot served as Solicitor-General for Ireland in the Liberal government of 1886, and as Attorney-General for Ireland in 1892, when he was made a member of the Irish Privy Council.