List of United Kingdom Parliament constituencies (1918–1945) by region

Between 1918 and 1945, the parliamentary constituencies of the United Kingdom were defined primarily by the Representation of the People Act 1918, which restructured the electoral system in response to post-war social and demographic changes. The Act enfranchised all men over the age of 21 and women over 30 who met minimum property qualifications, significantly expanding the electorate. It also redrew constituency boundaries to reflect population growth and urbanisation following the First World War.

This period saw seven general elections, from 1918 to 1935, conducted using these boundaries. The constituencies remained largely unchanged until the implementation of the Representation of the People Act 1948, which introduced single-member constituencies and equal representation by population, effective from the 1950 general election. The political implications of these reforms, and the evolving role of Parliament during this time, have been analysed by scholars such as Vernon Bogdanor, and documented in reference works by David and Gareth Butler.

South West (43)

Cornwall (5) Constituency19181922192319241929193119351945Bodmin Co. Conservative Liberal Liberal Conservative Liberal Liberal Conservative ConservativeCamborne Liberal National Liberal Independent Liberal Constitutionalist Liberal Conservative Conservative ConservativeCornwall North Liberal National Liberal Liberal Conservative Liberal Liberal Liberal LiberalPenryn and Falmouth Co. Conservative Conservative Liberal Conservative Liberal Conservative Conservative LabourSt Ives Coalition Liberal Conservative Liberal Conservative Liberal Liberal National Liberal National Liberal National

Devon (11) Constituency19181922192319241929193119351945Barnstaple Coalition Liberal Conservative Liberal Conservative Conservative Conservative Liberal ConservativeExeter Co. Conservative Conservative Conservative Conservative Ind. Conservative Conservative Conservative ConservativeHoniton Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativePlymouth Devonport Co. Conservative Conservative Liberal Liberal Liberal Liberal National Liberal National LabourPlymouth Drake Co. Conservative Conservative Conservative Conservative Labour Conservative Conservative LabourPlymouth Sutton Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative LabourSouth Molton Coalition Liberal Liberal Liberal Conservative Liberal Liberal National Liberal National Liberal NationalTavistock Co. Conservative Liberal Liberal Conservative Conservative Conservative Conservative ConservativeTiverton Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeTorquay Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeTotnes Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative Conservative

Somerset (7) Constituency19181922192319241929193119351945Bath Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeBridgwater Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative Ind. ProgressiveFrome Co. Conservative Conservative Labour Conservative Labour Conservative Conservative LabourTaunton Co. Conservative Liberal Liberal Conservative Conservative Conservative Conservative LabourWells Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeWeston-super-Mare Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeYeovil Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative Conservative

Dorset (4) Constituency19181922192319241929193119351945Dorset East Coalition Liberal Ind. Conservative Conservative Conservative Liberal Conservative Conservative ConservativeDorset North Co. Conservative National Liberal Liberal Conservative Conservative Conservative Conservative LiberalDorset South Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeDorset West Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative Conservative

Gloucestershire (11) Constituency19181922192319241929193119351945Bristol Central Co. Conservative Conservative Conservative Conservative Labour Conservative Conservative LabourBristol East Coalition Liberal National Liberal Labour Labour Labour Labour Labour LabourBristol North Coalition Liberal Liberal Labour Liberal Labour Liberal Liberal Labour Co-opBristol South Coalition Liberal National Liberal Liberal Liberal Labour Conservative Labour LabourBristol West Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeCheltenham Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative Ind. ConservativeCirencester and Tewkesbury Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeForest of Dean Labour Labour Labour Labour Labour National Labour Labour LabourGloucester Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative LabourStroud Coalition Liberal Conservative Liberal Conservative Conservative Conservative Conservative LabourThornbury Coalition Liberal Conservative Liberal Conservative Conservative Conservative Conservative Labour

Wiltshire (5) Constituency19181922192319241929193119351945Chippenham Co. Conservative Liberal Liberal Conservative Conservative Conservative Conservative ConservativeDevizes Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeSalisbury Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeSwindon Co. Conservative Conservative Conservative Conservative Labour Conservative Conservative LabourWestbury Co. Conservative Liberal Liberal Conservative Conservative Conservative Conservative Conservative

South East (including London) (148; 161 in 1945)

Oxfordshire (3) Constituency19181922192319241929193119351945Banbury Coalition Liberal Conservative Conservative Conservative Conservative Conservative Conservative ConservativeHenley Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeOxford Co. Conservative Liberal Liberal Conservative Conservative Conservative Conservative Conservative

Buckinghamshire (3; 4 in 1945) Constituency19181922192319241929193119351945Aylesbury Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeBuckingham Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative LabourEton and Slough LabourWycombe Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative Labour

Berkshire (4) Constituency19181922192319241929193119351945Abingdon Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeNewbury Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeReading Co. Conservative Conservative Labour Conservative Labour Conservative Conservative LabourWindsor Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative Conservative

Hampshire (12) Constituency19181922192319241929193119351945Aldershot Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeBasingstoke Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeBournemouth National Party Conservative Conservative Conservative Conservative Conservative Conservative ConservativeFareham Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeNew Forest and Christchurch Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativePetersfield Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativePortsmouth Central Liberal Conservative Liberal Conservative Labour Conservative Conservative LabourPortsmouth North Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative LabourPortsmouth South Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeSouthampton (Two members) Coalition Liberal Conservative Conservative Conservative Labour Liberal National Liberal National Labour Coalition Liberal Conservative Conservative Conservative Labour Conservative Conservative LabourWinchester Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative Labour

Isle of Wight (1) Constituency19181922192319241929193119351945Isle of Wight Co. Conservative Liberal Liberal Conservative Conservative Conservative Conservative Conservative

Surrey (12; 14 in 1945) Constituency19181922192319241929193119351945Chertsey Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeCroydon North Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeCroydon South Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative LabourEpsom Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeFarnham Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeGuildford Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeKingston upon Thames Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeMitcham Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative LabourCarshalton ConservativeSutton and Cheam ConservativeReigate Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeRichmond (Surrey) Co. Conservative Ind. Conservative Conservative Conservative Conservative Conservative Conservative ConservativeSurrey East Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeWimbledon Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative Labour

Sussex (9; 10 in 1945) Constituency19181922192319241929193119351945Brighton (Two members) Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative Conservative Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeChichester Co. Conservative Conservative Liberal Conservative Conservative Conservative Conservative ConservativeEastbourne Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeEast Grinstead Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeHastings Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeHorsham and Worthing Co. Conservative Conservative Conservative Conservative Conservative Conservative ConservativeN/AHorsham ConservativeWorthing ConservativeLewes Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative ConservativeRye Co. Conservative Conservative Conservative Conservative Conservative Conservative Conservative Conservative

Kent (15; 17 in 1945)