Lagan Valley (UK Parliament constituency)

Lagan Valley is a parliamentary constituency in the United Kingdom House of Commons.

Quick Facts Major settlements, Current constituency ...

Lagan Valley
County constituency for the House of Commons
Interactive map of boundaries from 2024
Location within Northern Ireland
Major settlements	Lisburn
Current constituency
Created	1983
Member of Parliament	Sorcha Eastwood (Alliance)
Seats	1
Created from	South Antrim, Belfast South, North Down and South Down[1]

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The constituency had always returned unionist MPs from its creation until 2019, However it returned Sorcha Eastwood of the Alliance Party in the 2024 election.^[2]

For the history of the equivalent constituencies prior to 1950, see Antrim (UK Parliament constituency) and Down (UK Parliament constituency) and from 1950 until 1983, please see South Antrim (UK Parliament constituency) and North Down.

Map of boundaries 2010–2024

1983–1997: The District of Lisburn, and the Borough of Castlereagh ward of Carryduff.

1997–2010: The District of Lisburn wards of Ballinderry, Ballymacash, Ballymacbrennan, Ballymacoss, Blaris, Derryaghy, Dromara, Drumbo, Dunmurry, Glenavy, Harmony Hill, Hilden, Hillhall, Hillsborough, Knockmore, Lagan Valley, Lambeg, Lisnagarvey, Maghaberry, Magheralave, Maze, Moira, Old Warren, Seymour Hill, Tonagh, and Wallace Park, and the District of Banbridge wards of Dromore North, Dromore South, Gransha, and Quilly.

2010–2024: The City of Lisburn wards of Ballinderry, Ballymacash, Ballymacbrennan, Ballymacoss, Blaris, Dromara, Drumbo, Harmony Hill, Hilden, Hillhall, Hillsborough, Knockmore, Lagan Valley, Lambeg, Lisnagarvey, Maghaberry, Magheralave, Maze, Moira, Old Warren, Seymour Hill, Tonagh, Wallace Park, and part of Derryaghy; the District of Banbridge wards of Dromore North, Dromore South, Gransha, and Quilly and the Ballynahatty and Edenderry parts of the Belvoir ward of the City of Belfast.

2024–present: The District of Armagh, Banbridge and Craigavon wards of Aghagallon, Donaghcloney, Dromore, Gransha, Magheralin, and Quilly; and the District of Lisburn and Castlereagh wards of Ballinderry, Ballymacash, Ballymacbrennan, Ballymacoss, Blaris, Dromara, Harmony Hill, Hilden, Hillhall, Hillsborough, Knockmore, Lagan, Lagan Valley, Lambeg, Lisnagarvey, Maghaberry, Magheralave, Maze, Moira, Old Warren, Ravernet, Wallace Park, and White Mountain.

The seat was created in 1983, as part of an expansion of Northern Ireland's constituencies from 12 to 17, and was predominantly made up from parts of South Antrim and North Down. In their original proposals, in January 1980, the boundary commission proposed calling it 'Lagan'. In further revisions in 1995 it lost some areas to both Belfast West and Strangford.

Following their review of all parliamentary seats in Northern Ireland prior to the 2010 United Kingdom general election the Boundary Commission for Northern Ireland made alterations to Lagan Valley. In an unprecedented decision, passed by Parliament through the Northern Ireland Parliamentary Constituencies Order,^[3] one electoral ward was split between two constituencies. This followed concerns in Derriaghy about being moved into the neighbouring but republican West Belfast seat.

The Member of Parliament since 1997 was Sir Jeffrey Donaldson who was elected as a member of the Ulster Unionist Party but switched to the Democratic Unionist Party in 2004. He succeeded James Molyneaux who had represented the seat for the UUP since the 1983 general election and previously sat for the old South Antrim constituency which covered much of the same area. Donaldson was elected Leader of the DUP in June 2021, but resigned the leadership in March 2024.

• List of parliamentary constituencies in Northern Ireland