Armagh (UK Parliament constituency)

County Armagh had been represented by two seats in the Irish House of Commons.

From 1 January 1801, when the Acts of Union 1800 came into effect, it was represented by a county constituency with two MPs in the United Kingdom House of Commons.

It was not until the householder franchise was introduced for county elections, in the electoral reforms which took effect in 1885, that most (but not all) adult males became voters.

In these circumstances, most members of parliament came from a limited number of Protestant aristocratic and gentry families.

In 1974 the Ulster Unionist Party repudiated the Sunningdale Agreement and so did not reselect the pro-Sunningdale MP, John Maginnis.

In by-elections to fill a single seat, the first past the post system applied.