Career
Born in Graddum, County Cavan, Nixon became a district inspector in the Royal Irish Constabulary, and transferred to its successor in the new province of Northern Ireland, the Royal Ulster Constabulary (RUC). By 1922, he was responsible for controlling access to the Roman Catholic Ardoyne and "Bone" areas of Belfast, and worked closely with the Ulster Special Constabulary. Irish nationalist writer and activist Michael Farrell has alleged that during this period he led the Cromwell Club, an unofficial organisation of security officials responsible for killing several Catholic civilians.
These allegations have not been independently confirmed and during his lifetime Nixon successfully sued the Derry Journal and a book publisher for libel.
This contravened RUC regulations, and he was dismissed on the orders of Prime Minister James Craig. Nixon was elected to the Belfast Corporation as an Independent Unionist, but at the Northern Ireland general election, 1925, he stood unsuccessfully as an Ulster Unionist Party candidate in Belfast North.
In 1929, running once again as an Independent Unionist, he was narrowly elected as the Member of Parliament for Belfast Woodvale. From September 1932 until the 1933 election, he was the only opposition Member of Parliament attending the Parliament.
Nixon held his seat until his death in 1949, denying the murder allegations against him until the end of his life.