 He was Financial Secretary to the Treasury from 1964 to 1967, and retired from the Commons at the 1970 general election.From 1970 to 1990, he was Secretary-General of the International Commission of Jurists, succeeding Sean MacBride.He was the grandson of Hugh Hyacinth O'Rorke MacDermot, who served as Solicitor General for Ireland in 1885 and 1886, and as Attorney General for Ireland in 1892.