However the Sinn Féin Member of Parliament (MP) was unseated on petition on the basis that his Irish Republican Army (IRA) convictions made him ineligible, and in subsequent by-elections the seat was won by the Ulster Unionist Party (UUP).

Dunlop held his seat for the next nine years, though in 1975 he was part of a large section of Vanguard that broke away to form the short-lived United Ulster Unionist Party.

The 1983 general election saw a fierce contest for the seat, with the UUP, DUP, SDLP and Sinn Féin all polling strongly.

Following the boundary changes, McCrea contested the new Mid Ulster in 1997 but, by then, Sinn Féin had established itself as the most likely party to outpoll a unionist and so drew votes from the SDLP, resulting in Martin McGuinness winning.

On 11 June 2012, McGuinness announced his intention to resign from the House of Commons to concentrate on his position as Deputy First Minister and avoid so-called 'double jobbing' by which members of the Northern Ireland Assembly also work as councillors or MPs.

The seat was awarded to Beattie on petition on the grounds that Mitchell's conviction as a felon made him ineligible to sit in Parliament.

However, Beattie in turn was also found ineligible to sit due to holding an office of profit under the crown, triggering a further by-election.

Mitchell was subsequently unseated by a resolution of the House of Commons, on the grounds that his terrorist convictions made him ineligible to sit in Parliament.