Born in Drogheda, but resident in Mullaghbawn, South Armagh since childhood, O'Hanlon studied at University College Dublin. Prominent in the Northern Ireland Civil Rights Association, he was elected at the 1969 Northern Ireland general election, as an independent Nationalist MP for South Armagh. In August 1970, he was a founder member of the Social Democratic and Labour Party (SDLP).
O'Hanlon stood for the Westminster constituency of Armagh at the February 1974 general election, taking second place, with 29.3% of the votes cast. He stood for the Northern Ireland Constitutional Convention and the 1982 Assembly in Armagh, but on both occasions was narrowly beaten by fellow party member Hugh News.
O'Hanlon died on 7 April 2009 in Dublin's Mater Hospital following a short illness; he was 65 years old.
|Parliament of Northern Ireland|
Edward George Richardson
| Member of Parliament for South Armagh
|Northern Ireland Assembly (1973)|
|New assembly|| Assembly Member for Armagh