Known by his third forename, O'Neill was the first Speaker of the new Northern Ireland Parliament, created in 1921, a post he held until 1929 (a baronetcy was created for him that year).

Educated at Eton, like many of his relatives, and New College, Oxford, he was called to the English Bar at Inner Temple, London, in 1909, having served in the North of Ireland Yeomanry from 1902-1907; he practised on the North-East Circuit. He had a relatively early interest in politics, contesting Stockport for the Conservative and Unionist Party in the 1906 General Election, but was unsuccessful in that famous Liberal landslide. He served in the Royal Irish Rifles from the beginning of the First World War, during which time he was elected MP for mid-Antrim (unopposed) at the by-election of 1915, following his brother, AEB O'Neill, who in November 1914 had become the first serving MP to be killed in action during the war. Hugh became a Captain on the General List and ended the war with the rank of Major.

He remained a Westminster MP until 1952 (in 1951 he had become Father of the House). He was a United Kingdom Privy Councillor, a Northern Ireland Privy Councillor,  Chairman of the Conservative Members' (‘1922') Committee from 1935 to 1939 and Parliamentary Under-Secretary of State for India and Burma from 1939 to 1940. He also held the position of Lord Lieutenant of County Antrim from 1949 to 1959.

He was created 1^st Baron Rathcavan of The Braid in the County of Antrim in 1953; on his death he was succeeded by his son Phelim, who himself would become prominent in Northern Ireland politics.

Born:	8 June 1883
Died:	28 November 1982