The seat was re-created in 1950 when the old two MP Down constituency was abolished as part of the move to single member seats. Originally the seat consisted of most of the northern parts of County Down, with the south included in South Down. In January 1980, the Boundary Commission's original proposals suggested significantly reducing the size of the constituency and renaming it 'Loughside' on the grounds that this would avoid confusion in the event of borough council elections being held on the same day. As a result, in 1983 the seat was radically cut down as part of an expansion of Northern Ireland's constituencies from 12 to 17, although the name remained unaltered. Significant parts of the constituency were transferred to the new Strangford constituency. In boundary changes proposed by a review in 1995, the seat exchanged territory with Strangford, losing the Dundonald area from Castlereagh and gaining a part of Ards.