Every 5 years, the Boundary Commissions for England, Scotland, Wales and Northern Ireland review the UK parliamentary constituency boundaries.

The last completed Boundary Review recommended 650 constituencies, and took effect at the General Election in 2010.

Office for National Statistics

The Office for National Statistics (ONS) has produced a guide to parliamentary constituencies and a map of the current constituencies.

The Office for National Statistics publishes a CSV file listing the names and codes for each parliamentary constituency (650 in total), under the Open Government License.

“The nine-character codes are created by the ONS. The England and Wales names are statutory names taken from the Statutory Instrument (SI). The Northern Ireland nine character codes and names were supplied by NISRA (Northern Ireland Statistics and Research Agency). The Scotland names and nine character codes have been sourced from the National Records of Scotland (NRS).”

Constituency names

The parliamentary constituencies of England are named in The Parliamentary Constituencies (England) Order 2007. Wikipedia contains a history of the constituency redistributions.

Ordnance Survey Shapefile

The Ordnance Survey produces the Boundary-Line data, which includes an ESRI Shapefile for the boundary of each parliamentary constituency. The Boundary-Line data is published under the OS OpenData license, which incorporates the Open Government License.

Identifiers

The Ordnance Survey’s administrative geography and civil voting area ontology includes a “hasUnitID” property, which provides a unique ID for each region, and a “GSS” property that is the ONS’ code for each region.

SPARQL

The Boundary-Line SPARQL interface can be used to retrieve the GSS, Unit ID and name for each parliamentary constituency:

select ?name ?gss ?unit_id
where
{
  ?x a <http://data.ordnancesurvey.co.uk/ontology/admingeo/WestminsterConstituency> ;
    <http://www.w3.org/2000/01/rdf-schema#label> ?name ;
    <http://data.ordnancesurvey.co.uk/ontology/admingeo/gssCode> ?gss ;
    <http://data.ordnancesurvey.co.uk/ontology/admingeo/hasUnitID> ?unit_id .
 }

CartoDB

The Boundary-Line Shapefile includes the Unit ID (OS) and GSS (ONS) code for each constituency, so they can easily be used to merge the boundary polygons with other data sources in CartoDB.

If using CartoDB’s free plan, it is necessary to use a version of the Boundary-Line Shapefile with simplified polygons, to reduce the size of the data.

View the UK parliamentary constituencies in CartoDB.

Future

Following the next Boundary Review, the number of constituencies will be reduced from 650 to 600 by the Parliamentary Voting System and Constituencies Act, introduced by the current coalition government.

"The key change is that the number of voters in each constituency will have to be within 5% of 76,641 - this is the figure gained by dividing the UK electorate of 45,678,175 by 596."