Isleworth, Brentford and Chiswick: New Boundaries 2018 Calculation

Isleworth, Brentford and Chiswick: Overview

 Projection: LAB seat 

Implied MP at 2017: Ruth Cadbury  (LAB)
County/Area: Hounslow (London)
Electorate: 72,875
Turnout: 74.6%

 Implied 2017 VotesImplied 2017 Share
LAB28,49752.4%
CON21,76740.0%
LIB3,5596.5%
Green4490.8%
UKIP760.1%
OTH180.0%
LAB Majority6,73012.4%

See overview of other seats in London.

Isleworth, Brentford and Chiswick : Political and Demographic indicators

The table below shows some political and demographic numerical indicators for the new Isleworth, Brentford and Chiswick constituency, the 'London' area and nation.

The political measures include the Left/Right and International/National axes (what does this mean).

The demographic measures are from the 2011 Census and include categories relating to national identity, economic activity, health and education. These categories are those which have the most relevance to political attitudes.

IndicatorSeatLondonAll GB
Party WinnerLABLABCON
Economic Position16° Right11° Right
National Position30° Int29° Int1° Int
EU Leave %38%40%52%
British Identity23%38%29%
Good Health45%50%48%
UK Born91%64%88%
Good Education31%48%39%
Good Job56%61%51%
High SEC55%55%51%
Average Age50.644.148.5
ABC1 Class55%62%53%

Isleworth, Brentford and Chiswick ranks #535 for "Leave", #29 for "Right" and #562 for "National" out of 600 new seats.

Indicators: Legend and Descriptions

Indicators : Legend and Descriptions

The colour scheme used in the table above is explained in the legend table below. The eight census indicators (British Identity, Good Health, UK Born, Good Education, Good Job, High SEC, Average Age and AB1 Class) all use the same 'Census' colour scheme indicating whether the area's level is above or below the national average.

TopicCat 1Cat 2Cat 3Cat 4Cat 5
Economic PositionVery LeftLeftCentristRightVery Right
National PositionVery IntInternationalCentristNationalVery Nat
EU Leave %Very RemainRemainBalancedLeaveVery Leave
CensusVery LowLowMediumHighVery High

Indicator definitions are given in terms of political data definitions or census categories:

IndicatorCensus
Question
Definition / Included Census Categories
Party WinnerArea party winner : actual election result or projected by Electoral Calculus
Economic PositionEconomic position between 100° Left and 100° Right, estimated by Electoral Calculus from political and demographic data.
National PositionNational position between 100° International and 100° National, estimated by Electoral Calculus from political and demographic data.
EU Leave %EU Referendum vote share for 'Leave' : actual result or estimate
British IdentityNational Identity (KS202)Those answering British, British-Other, or Scottish-British
Good HealthHealth (KS301)Those answering 'Very Good Health'
UK BornCountry of Birth (QS203)Those answering England, Northern Ireland, Scotland, Wales, GB Other, or UK Other
Good EducationHighest level of Qualification (QS501)Level 3 (A-level equivalent) or Level 4+ (degree equivalent)
Good JobOccupation (QS606)Occupation codes 1xx to 4xx (Managers, Professionals, Associates, and office workers)
High SECNS-SeC of Household Reference Person (QS609)National Statistics Socio-economic Classification from 1 to 4 (higher managers and professionals, lower managers and professionals, intermediate occupations, small employers and self-employed).
Average AgeAge (QS103)Average age of adults (18 years and above)
ABC1 ClassApproximated Social Grade (QS611)Approximated social grades A, B and C1

Isleworth, Brentford and Chiswick: Map

Boundary Lines courtesy of Ordnance Survey OpenData © Crown copyright 2015

Introduction

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Isleworth, Brentford and Chiswick been in force at that time. The basic idea of the calculation is to look at the district council wards which make up the new seat, and estimate how they voted in 2017. This estimate is based on the recent local election results in those wards, with adjustments made to allow for different turnouts and different voting patterns for local and general elections.

In many cases, wards are divided between several old constituencies or between new constituencies. So the same ward may be shown more than once, but the electorate shown will reflect that ward sub-section.

Election results from a recent local election are given. This is usually the local election closest to 2015 from the period 2012-2015. For multiple-member wards, the votes shown are the sum of the votes cast for all candidates of each party. A negative number indicates candidate(s) elected unopposed.

Calculation method

There are two problems with using the raw (actual) local election results to imply general election results ward-by-ward. Firstly, turnout can be different between local and general elections, which means that the total number of local votes cast does not equal the number of votes cast in each old seat at the general election. To correct for this, we adjust the local votes to match the general election turnout. Each ward's result is scaled, whilst keeping constant the percentage support for each party, so that the total turnout adds up to the old seat's general election turnout. All wards in the old seat are assumed to have the same percentage turnout.

Secondly, even though we now have the correct number of votes in the old seat, the party totals will not match the general election result. Some parties do better at the local election than the general election, and others do vice versa. We call these strong and weak parties respectively. The next step is to transfer votes from strong parties to weak parties. This is done by taking votes proportionally away from strong parties and putting them in a transfer pool. For instance if a party got 12,500 local votes, but only 10,000 general election votes, it will lose 20% over all the wards. These votes in each ward will be put in the ward's transfer pool and allocated to the weak parties. Weak parties will get votes transferred to them in proportion to the votes they need over the old seat. For instance, if two weak parties need 4,000 and 1,000 votes respectively, the first party will get 80% of each ward's transfer pool and the second party will get 20% of each ward's transfer pool. The transfer of votes between parties is done using the Electoral Calculus Transition Model.

More details of the calculation formulas are available.

List of old seats forming part of Isleworth, Brentford and Chiswick

The old seat(s) needed are:

Old seat: Brentford and Isleworth

The table shows the transfer-adjusted results for each ward in the old seat of Brentford and Isleworth, as well as showing which new seat each ward is in.

Old seat: Brentford and IsleworthTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
HounslowBrentford9,506Isleworth, Brentford and Chiswick1,9104,559412000006,881
HounslowChiswick Homefields7,488Isleworth, Brentford and Chiswick2,7742,274372000005,420
HounslowChiswick Riverside7,649Isleworth, Brentford and Chiswick2,8462,374316000005,536
HounslowHounslow Central10,037Feltham and Hounslow2,1104,891263000007,264
HounslowHounslow Heath9,751Feltham and Hounslow1,8694,911277000007,057
HounslowHounslow South7,567Feltham and Hounslow2,1363,082258000005,476
HounslowIsleworth7,973Isleworth, Brentford and Chiswick1,7543,809208000005,771
HounslowOsterley and Spring Grove8,602Isleworth, Brentford and Chiswick2,8343,145247000006,226
HounslowSyon8,978Isleworth, Brentford and Chiswick2,0884,080330000006,498
HounslowTurnham Green7,600Isleworth, Brentford and Chiswick2,8612,241399000005,501
 Total85,151 23,18235,3663,0820000061,630

The full details of these calculations are given on the Brentford and Isleworth seat details page. Click on "Show workings".

Old seat: Ealing Central and Acton

The table shows the transfer-adjusted results for each ward in the old seat of Ealing Central and Acton, as well as showing which new seat each ward is in.

Old seat: Ealing Central and ActonTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
EalingActon Central9,635Ealing and Acton2,0044,889294000007,187
EalingEaling Broadway8,714Ealing and Acton2,8283,223448000006,499
EalingEaling Common8,757Ealing and Acton2,4143,583535000006,532
EalingEast Acton11,684Ealing and Acton2,4126,119185000008,716
EalingHanger Hill9,776Ealing and Acton3,4873,341464000007,292
EalingSouth Acton8,880Ealing and Acton1,8384,561223000006,622
EalingSouthfield8,391Isleworth, Brentford and Chiswick2,2083,394657000006,259
EalingWalpole8,363Ealing and Acton2,0393,928269000006,236
 Total74,200 19,23033,0383,0750000055,343

The full details of these calculations are given on the Ealing Central and Acton seat details page. Click on "Show workings".

Old seat: Ealing Southall

The table shows the transfer-adjusted results for each ward in the old seat of Ealing Southall, as well as showing which new seat each ward is in.

Old seat: Ealing SouthallTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
EalingDormers Wells9,041Southall and Heston1,0704,931192361200216,262
EalingElthorne9,569Ealing and Acton1,8473,64557217734300436,627
EalingLady Margaret9,424Southall and Heston1,4604,7401341115800246,527
EalingNorthfield9,059Isleworth, Brentford and Chiswick2,4922,6216187644900186,274
EalingNorwood Green9,340Southall and Heston1,2045,000127218500336,470
EalingSouthall Broadway8,988Southall and Heston7325,153116821001956,225
EalingSouthall Green9,767Southall and Heston8245,631134757000296,763
 Total65,188 9,62931,7211,8935041,0380036345,148

The full details of these calculations are given on the Ealing Southall seat details page. Click on "Show workings".

New seat: Isleworth, Brentford and Chiswick

The new seat of Isleworth, Brentford and Chiswick is made up of the following wards, with the transfer-adjusted votes shown.

New seat: Isleworth, Brentford and Chiswick
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
EalingNorthfield8,575Ealing Southall2,4922,6216187644900186,274
EalingSouthfield8,987Ealing Central and Acton2,2083,394657000006,259
HounslowBrentford9,080Brentford and Isleworth1,9104,559412000006,881
HounslowChiswick Homefields7,051Brentford and Isleworth2,7742,274372000005,420
HounslowChiswick Riverside7,590Brentford and Isleworth2,8462,374316000005,536
HounslowIsleworth7,540Brentford and Isleworth1,7543,809208000005,771
HounslowOsterley and Spring Grove8,361Brentford and Isleworth2,8343,145247000006,226
HounslowSyon8,723Brentford and Isleworth2,0884,080330000006,498
HounslowTurnham Green6,968Brentford and Isleworth2,8612,241399000005,501
 Total72,875 21,76728,4973,55976449001854,366

And these are the implied results for 2017 for the new seat of Isleworth, Brentford and Chiswick.


© 2017 Martin Baxter
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