5. 2010 General Election: New Constituencies

SN/SG/5280 RESEARCH PAPER 10/02

Revised constituency areas 5. 2010 General Election: new constituencies; seats and swing The new areas for this election are the result of the latest round of boundary changes, unusual in that it has been implemented in stages. Summary New constituency areas were introduced in Scotland for the 2005 General The 2010 General Election will use new constituency boundaries in Election, and these will be unchanged in 2010. New constituency areas England, Wales and Northern Ireland. In Scotland the boundaries will be will be used in England, Wales and Northern Ireland for the 2010 General the same as 2005. After the election there will be 650 seats in the House Election. of Commons, four more than the 646 now. In partisan terms, the new areas give a net benefit to the Conservatives. If the 2005 election had been fought on the new boundaries the Conservatives would have gained Constituencies by country around 12 additional seats and Labour seven fewer. Country 2005 2010 Assuming a uniform national swing at the next General Election, Labour England 529 533 loses its overall majority if there is a swing of 1.6% or more from Labour to Scotland 59 59 the Conservatives compared with the 2005 General Election. A 4.3% Wales 40 40 Labour to Conservative swing would produce a House of Commons with Northern Ireland 18 18 the Conservatives as the largest party; and a swing of 6.9% would give the Conservatives an overall majority. A Labour to Conservative swing of United Kingdom 646 650 anything between 1.6% and 6.9% would result in a hung parliament, where no single party has more than half the seats. Overall, England will have four additional seats, while the number in Electoral swing Scotland, Wales and Northern Ireland will remain the same as now. The The swing from Party A to Party B is the average of the percentage modest increase in the number of constituencies in England disguises point fall in Party A’s share of the vote and the percentage point rise in changes in seat numbers in different parts of the country. In England, 11 Party B’s – this conventional definition for two-party swing is used shire counties each gain a seat, while each of the former Metropolitan throughout this note. areas and Greater London lose a seat. This is largely a reflection of

population movement from urban to suburban and rural areas. A 1% swing from one party to another involves adding 1% point of votes to one party and subtracting 1% point of votes from the other.

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Index of change – Hampstead and Kilburn, example Extent of change The new constituency of Hampstead and Kilburn has the former In 2005, the reduction of seats in Scotland resulted in significant changes constituency of Hampstead and Highgate as its base. 48,496 electors in almost all seats – around half of electors there were “moved” from, or from an electorate of 64,616 in Hampstead and Highgate are into a new area. In 2010, the changes in England, Wales and Northern transferred to Hampstead and Kilburn. This leaves 16,120 who are Ireland are less radical. In 79 of these constituencies there is no transferred to a different constituency. A further 26,077 electors come geographic change at all (although in some cases constituency names from the old Brent East and South constituencies. The resultant may change). And in more than half of constituencies (331, equivalent to electorate for Hampstead and Kilburn is 74,573 (48,496 + 26,077) 56%) the number leaving their old constituency or being added to the new one as a proportion of the electorate is 10% or less. This index of change The index of change for the new area is 65.3%. is more than 50% in just 77 (13%) of constituencies in England, Wales and (16,120 + 26,077) / 64,616 = 65.3 Northern Ireland.

Extent of change in constituency boundaries converging around the country averages, the “electoral quota”. This reduces some of the variation around the averages for the old Index of change Northern constituency electorates. In England, 399 of the former constituencies %(a) England Wales Ireland E W & NI were within +10% of the quota, and 14 were more than +20% of the quota. 05518679 For the new constituencies, 474 are within +10% of the quota and only 0-10 228 18 6 252 one (the Isle of Wight) is more than 20% beyond it. 10-25 105 1 4 110 25-50 70 1 2 73 50+ 75 2 0 77 Political impact of the new areas All 533 40 18 591 Following the 2005 Election, Labour’s 355 MPs gave it 64 more seats than (a) The sum of electors leaving and joining the base constituency as a percentage of all the other parties combined (including the Speaker). Had the 2005 the electorate of that constituency election been fought on the new boundaries Labour would have won 349 of the 650 seats.1 This would have given them 48 more seats than all the Size of constituency electorates other parties combined. The Conservatives won 198 seats in 2005, while on the new boundaries could have expected to have won 210, 12 more; One of the aims of the boundary changes is to reduce disparities in size Labour could have won seven fewer seats; and Plaid Cymru would have between constituencies in each country in the UK. In each country the changes have resulted in the electorates in individual constituencies 1 Based on Rallings & Thrasher (2007)

xiv SN/SG/5280 RESEARCH PAPER 10/02 two seats instead of three. The number of Liberal Democrat seats would Change in seats and Labour to Conservative swing be unchanged as individual gains and losses offset each other. To produce: Seats % swing Labour majority of 20 -14 1.0 House of Commons 2005 election Labour loss of overall majority -24 1.6 New boundaries (notional results) Conservatives as largest party 72 4.3 Seats Conservative overall majority 116 6.9 Labour 349 Conservative majority of 20 125 7.6 Conservative 209 Liberal Democrat 62 Note: assumes uniform national swing Plaid Cymru 2 SNP 6 Swing in previous General Elections N Ireland 18 Other 4 The 1979 Conservative election victory was the result of a 5.3% point Lab- All 650 Con swing; in 1997, there was a Con-Lab swing of 10.2% points. With these two exceptions, swing between the two main parties at General Source: Rallings & Thrasher (2007) Elections has not exceeded 5% points since 1950. For the Conservatives to win an overall majority requires a uniform national swing of 6.9%. This The gain in seats by the Conservatives as a result of the boundary would be higher than any election since 1950, except 1997. changes affects the swing2 that party requires for there to be a change in the governing party. In 2005, a swing of 2.0% from Labour to the Conservatives would have deprived it of its overall majority. On the basis General Election swings: Labour to Conservative Great Britain, percentage points of the new constituencies a Labour-Conservative swing of 1.6% would be sufficient. The Conservatives would become the largest party on a 4.3% 8 6 +4.9 +5.3 swing and would have an overall House of Commons majority with a swing +4.1 4 +2.9 +2.8 +3.1 +1.8 +1.8 from Labour of 6.9% or more. 2 +1.1 +1.2 0 -2 -0.8 -2.2 -1.7 -2.1 -4 -3.1 -6 -8 -10 -12 -10.2 1950 1951 1955 1959 1964 1966 1970 1974 1974 1979 1983 1987 1992 1997 2001 2005 (F) (O)

2 The swing from Party A to Party B is the average of the percentage point fall in Party A’s The swing from the National Government to Labour in 1945 was 12.0%, share of the vote and the percentage point rise in Party B’s – this conventional definition for although it should be borne in mind that the circumstances in 1945 were two-party swing is used throughout this note.

xv SN/SG/5280 RESEARCH PAPER 10/02 unusual, not least that there had not been an election since 1935 and that Partly because Labour seats tend to be those with smaller electorates and National Labour candidates contributed 1.6 percentage points to the lower turnout than Conservative ones, and also because the Conservative National total in 1935. vote is concentrated in certain areas, it is possible in some cases for Labour to retain an overall majority of seats even if it has a lower share of the national vote (as in February 1974).

Projections of seats by Party for 2010 There are a number of ways in which national vote shares can be translated into seats won by individual parties. The table overleaf is based The UK’s first past the post electoral system means that national party on work of Rallings and Thrasher at Plymouth University. It suggests that vote shares are not directly translated into representation in the House of Conservatives could require a 10% point lead in the popular vote over Commons. However, it is possible to apply changes in the national vote Labour to have an overall majority of seats in the House of Commons. share since 2005 to individual constituency results to project the possible Labour, on the other hand, could achieve an overall majority where the composition of the House for each party. In 2010 this has an added national shares for the two main parties are much closer and, in some complication caused by changes in seat boundaries, so the 2005 base has cases, even with a slightly lower share of the vote than the Conservatives. to be notional rather than actual constituency results where the areas have For example, if both the Conservatives and Labour got 36% (the same as been changed. Labour’s share in 2005) of the national vote, the projected number of seats The results of applying across-the-board changes to the 2005 notional is 236 Conservative and 333 Labour. constituency votes to produce various national votes shares for Labour Swing seats and Conservative are presented in the graphic on page xviii. This shows the number of seats for the three main parties for a range of national Applying uniform Labour to Conservative swing to the notional 2005 Conservative and Labour vote-share combinations. If, for example, the results gives a list of the seats that would be most likely to change hands Conservatives were to get 40% of the vote and Labour 30%, on the basis under such scenario. In most cases these would be (notionally) Labour of the assumptions used, this would translate into a House of Commons seats gained by the Conservatives, although changing votes between the where the Conservatives have 318 seats and Labour 246. The two main parties does in some cases produce losses and gains for other Conservatives would be the largest party, but would be seven seats short parties. of an overall majority. On this basis, Labour losing Milton Keynes South would be signal its loss These projections are particularly dependent on the assumption of uniform of an overall majority. Hammersmith would be the 72nd Conservative gain change compared to the 2005 base. In practice the results in individual and would make the Conservatives the largest party in the Commons. areas may not conform to a national pattern. The 6.9% Labour-Conservative swing required for the Conservatives to get an overall majority would be indicated by the Conservatives gaining On the new boundaries, Labour starts with 349 seats (on a notional 2005 Cornwall North. On the basis of uniform Labour-Conservative swing base). The loss of 24 of these would cost Labour its overall majority. This th Cornwall North would be 116 on the Conservative’s “target” list. Seats would happen if there were a uniform national Lab-Con swing of 1.6%. won beyond that would add to a Conservative majority in the House of The Conservatives start with 210 seats (on the notional 2005 base). They Commons. need to win a further 116 seats to gain an overall majority.

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The graphic on pages xix-xx show which seats would change hands on Sources and additional information: the basis of successive 0.5% point Labour-Conservative swing. The two pages present these by the party losing and winning each seat were these 2005 General Election: Notional Results Great Britain (April 2008) HC swings to take place country-wide against notional 2005 election results. Library Note 4691

Marginal Seats HC Library Note 3373 (Sept 2008)

2001 Census of Population: Statistics for new Parliamentary Constituencies

Michael Thrasher & Colin Rallings Media Guide to the new constituencies www.plymouth.ac.uk/elections

Richard Cracknell xt 4632

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Projection of seats in the new House of Commons for different party vote shares % vote shares and seats in Great Britain

Conservative

28% 30% 32% 34% 36% 38% 40% 42% 44% Con 169 206 233 2 60 282 309 328 354 379 Conservative majority Labour 28% Lab 270 275 268 2 60254 241 228 215 205 LD 178 136 116 9 781 69 63 50 36 Conservative largest party, short of majority Maj -109 -99 -113 '' -85 -31 759109 Con 173 200 222 251 2 70 298 318 343 370 Labour largest party, short of majority 30% Lab 303 304 297285 2 70 259 246 233 218 LD 141 113 9881 7 7 62 54 43 32 Labour majority Maj-43-41-55-79 ''-53-13 37 91 Con 170 196 212 237 262 286 308 335 359 Maj Seats of largest party in excess of those of all the other parties (exc Speaker) 32% Lab 334 325 317304 290 275 264 252 238 LD 113 96 8876 65 57 46 32 23 Maj 19 1 -15 -41 -69 -77 -33 21 69 2005 notional baseline (GB) Con 168 185 210 223 251 274 299 322 347 Vote share % Seats 34% Lab 352 343 332 323 310 298 283 270 257 Labour 36.1 349 LD 98 90 76 72 56 47 37 28 17 Conservative 33.2 209 Maj 55 37 15 -3 -29 -53 -51 -5 45 Liberal Democrat 22.6 62 Con 164 176 199 220 236 262 289 313 333 Other (inc Speaker) 8.1 92 36% Lab 367 361 352 343 333 318 304 289 274 Majority 49 LD 89 83 69 56 50 41 28 19 13 Maj 85 73 55 37 17 -13 -41 -23 17 Con 163 177 187 211 229 249 274 300 319 38% Lab 376 377 371 359 349 340 325 309 293 LD 82 67 62 50 42 33 23 13 11 Maj 103 105 93 69 49 31 1 -31 -11 Con 164 176 187 199 220 244 263 284 306 40% Lab 384 383 383 378 367 355 344 329 312 LD 74 62 51 44 34 24 16 10 6 Maj 119 117 117 107 85 61 39 9 -25

Based on Rallings & Thrasher Media Guide to the New Parliamentary Constituencies Assum pti ons: Uniform swing across all constituencies from 2005 election, notional result for new constituencies Vote share for Liberal Democrats is 100% less (share for new Conservative, Labour and "others") "Others" is all parties except Conservative, Labour & Liberal Democrat, and their vote share is assumed to be as in 2005 18 Northern Ireland seats are excluded as are four other seats - Bethnal Green & Bow (Respect), Blaenau Gwent (Independent), Wyre Forest (IKHHC) and Buckingham (Speaker)

xviii SN/SG/5280 RESEARCH PAPER 10/02 Constituencies in GB changing parties with Con-Lab swing by losing and winning party (2005 -notional base)

Lab-Con Swing Seats changing party (colour shows party losing) Gillingham & Croydon Portsmouth Roms ey & Craw ley Harlow Battersea Rochdale York Outer Hove 0% to 0.5% Rainham Central North South'n N Milton Edinburgh Cheltenham Oxf ord East Stroud Dartford Loss of overall majority by Labour 0.5% to 1% Keynes N South Basildon S Ealing Chester, Somerton & Colne Cardiff Hastings & Calder Hampstead Ochil & S Eastleigh Stourbridge 1% to 1.5% & E Central & City Of Frome Valley North Rye Valley & Kilburn Perthshire Milton Islington S & Vale Of Sw indon W'morland Dors et N'thampton Corby Arfon High Peak Loughboro' Aberconw y Watford 1.5% to 2% Keynes S Finsbury Glamorgan South & Lonsdale South South Birmingham H'ford & S Brighton Stafford Broxtow e Burton 2% to 2.5% Edgbaston H'f ords hire Kemptow n

Plymout h Sut t on Dudley Elmet & Reading M'cambe & Bolton North Tynemouth Pudsey Ipsw ich Bolton West Waveney 5.5% to 6% & Devonport North Rothw ell West Lunesdale Eas t Sefton Sutton & Amber Barrow & Torbay Tooting Gloucester 6% to 6.5% Central Cheam Valley Furness Brighton Stockton Batley & Cornw all Thurrock Copeland Carlisle Kingsw ood Hyndburn 6.5% to 7% Pavilion South Spen North Weaver Renfrew shi Lancashire Vale Of Richmond Durham, Norw ic h Luton South Cheadle 7% to 7.5% Vale re East West Clw y d Par k City Of South

xix SN/SG/5280 RESEARCH PAPER 10/02 Lab-Con Swing Seats changing party (colour shows party gaining) Gillingham & Croydon Portsmouth Roms ey & Craw ley Harlow Battersea Rochdale York Outer Hove 0% to 0.5% Rainham Central North South'n N Milton Edinburgh Cheltenham Oxf ord East Stroud Dartford 0.5% to 1% Keynes N South Basildon S Ealing Chester, Somerton & Colne Cardiff Hastings & Calder Hampstead Ochil & S Eastleigh Stourbridge 1% to 1.5% & E Central & City Of Frome Valley North Rye Valley & Kilburn Perthshire Milton Islington S & Vale Of Sw indon W'morland Dors et N'thampton Corby Arfon High Peak Loughboro' Aberconw y Watford 1.5% to 2% Keynes S Finsbury Glamorgan South & Lonsdale South South Birmingham H'ford & S Brighton Stafford Broxtow e Burton 2% to 2.5% Edgbaston H'f ords hire Kemptow n

Wolverham C'mart hen W & South Derbyshire Bristol North Dumf ries & Carshalton Bury North Redditch Rugby Pendle Tamw orth 2.5% to 3% pton SW P'keshire S Ribble South West Gallow ay & Wallington Sw indon Aberdeen Taunton Westminste Per th & N Harrow Cleethorpes Worcester 3% to 3.5% North South Deane r North Perthshire Eas t Great Brigg & Conservatives become largest party Ynys Mon Eltham 3.5% to 4% Yarmouth Goole Chatham & Brentford & Bradford Rossendale Hammer s mit Blackpool N Lancaster & Dudley N'thampton Bedford Stevenage Hendon Angus Halifax Dew s bury 4% to 4.5% Aylesford Is lew orth West & Darw en h & Cleveleys Fleetw ood South North Warrington Leic'tershire Halesow en Wirral South Chippenham Lincoln Gedling Nuneaton 4.5% to 5% South NW & R' Regis Edinburgh N Warw ick & Poplar & Dov er Keighley Stirling 5% to 5.5% & Leith Leamington Limehouse Plymouth Dudley Elmet & Reading M'cambe & Bolton North Tynemouth Pudsey Ipsw ich Bolton West Waveney 5.5% to 6% Sutton & North Rothw ell West Lunesdale Eas t Sefton Sutton & Amber Barrow & Torbay Tooting Gloucester Conservatives gainoverall majority 6% to 6.5% Central Cheam Valley Furness Brighton Stockton Batley & Cornw all Thurrock Copeland Carlisle Kingsw ood Hyndburn 6.5% to 7% Pavilion South Spen North Weaver Renfrew shi Lancashire Vale Of Richmond Durham, Norw ic h Luton South Cheadle 7% to 7.5% Vale re East West Clw y d Par k City Of South

Constituencies in each line are arranged in ascending order by which a Labour to Conservative swing would change the winning party