Lewisham and Catford: New Boundaries 2018 Calculation

Lewisham and Catford: Overview

 Projection: LAB seat 

Implied MP at 2017: Heidi Alexander  (LAB)
County/Area: Lewisham (London)
Electorate: 72,781
Turnout: 78.5%

 Implied 2017 VotesImplied 2017 Share
LAB41,68872.9%
CON10,87119.0%
LIB2,0303.6%
Green1,0391.8%
UKIP8911.6%
OTH6321.1%
LAB Majority30,81753.9%

See overview of other seats in London.

Lewisham and Catford : Political and Demographic indicators

The table below shows some political and demographic numerical indicators for the new Lewisham and Catford 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 Position3° Left11° Right
National Position35° Int29° Int1° Int
EU Leave %37%40%52%
British Identity24%38%29%
Good Health45%50%48%
UK Born96%64%88%
Good Education37%48%39%
Good Job49%61%51%
High SEC49%55%51%
Average Age50.144.148.5
ABC1 Class51%62%53%

Lewisham and Catford ranks #541 for "Leave", #385 for "Right" and #578 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

Lewisham and Catford: 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 Lewisham and Catford 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 Lewisham and Catford

The old seat(s) needed are:

Old seat: Lewisham Deptford

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

Old seat: Lewisham DeptfordTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
LewishamBrockley11,952Greenwich and Deptford1,0246,319570042800538,394
LewishamCrofton Park10,378Dulwich and Sydenham1,2795,404391018400317,289
LewishamEvelyn11,526Greenwich and Deptford8736,487523094001198,096
LewishamLadywell10,080Lewisham and Catford1,0555,275367033300507,080
LewishamLewisham Central12,159Lewisham and Catford1,4206,573344015200518,540
LewishamNew Cross11,009Greenwich and Deptford1,0106,0893710133001287,731
LewishamTelegraph Hill11,368Greenwich and Deptford9026,3153460316001057,984
 Total78,472 7,56342,4622,91201,6400053755,114

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

Old seat: Lewisham East

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

Old seat: Lewisham EastTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
LewishamBlackheath9,230Greenwich and Deptford1,9933,673509216100576,395
LewishamCatford South10,216Lewisham and Catford1,5255,1701411137001057,079
LewishamDownham9,738Lewisham and Catford1,3634,5624043173500666,747
LewishamGrove Park9,796Lewisham and Catford2,0714,1471772418100706,787
LewishamLee Green9,675Greenwich and Deptford1,7214,247481416800816,702
LewishamRushey Green9,974Lewisham and Catford1,0265,40715911185001236,911
LewishamWhitefoot9,498Lewisham and Catford1,1614,8652152223700816,581
 Total68,127 10,86032,0712,0867988040058347,202

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

Old seat: Lewisham West and Penge

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

Old seat: Lewisham West and PengeTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
BromleyClock House10,770Beckenham3,0543,87364514712400167,859
BromleyCrystal Palace8,364Beckenham1,1794,0985928412700236,103
BromleyPenge and Cator11,854Beckenham2,1065,76047618010900198,650
LewishamBellingham10,177Lewisham and Catford1,2505,689223997900867,426
LewishamForest Hill10,240Dulwich and Sydenham1,3554,9757833826600557,472
LewishamPerry Vale10,781Dulwich and Sydenham1,6085,5683106222800907,866
LewishamSydenham10,716Dulwich and Sydenham1,6975,4492888921200857,820
 Total72,902 12,24935,4123,3176991,1450037453,196

The full details of these calculations are given on the Lewisham West and Penge seat details page. Click on "Show workings".

New seat: Lewisham and Catford

The new seat of Lewisham and Catford is made up of the following wards, with the transfer-adjusted votes shown.

New seat: Lewisham and Catford
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
LewishamBellingham9,019Lewisham West and Penge1,2505,689223997900867,426
LewishamCatford South9,413Lewisham East1,5255,1701411137001057,079
LewishamDownham9,072Lewisham East1,3634,5624043173500666,747
LewishamGrove Park9,249Lewisham East2,0714,1471772418100706,787
LewishamLadywell8,688Lewisham Deptford1,0555,275367033300507,080
LewishamLewisham Central10,532Lewisham Deptford1,4206,573344015200518,540
LewishamRushey Green8,053Lewisham East1,0265,40715911185001236,911
LewishamWhitefoot8,755Lewisham East1,1614,8652152223700816,581
 Total72,781 10,87141,6882,0308911,0390063257,151

And these are the implied results for 2017 for the new seat of Lewisham and Catford.


© 2017 Martin Baxter
Powered by TigerLib (11-Sep-2017 15:41)