New Seat Details - Altrincham and Knutsford

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Altrincham and Knutsford 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.

Party	Implied 2017 Votes	Implied 2017 Share
CON	31,166	52.6%
LAB	21,904	37.0%
LIB	4,585	7.7%
Green	1,041	1.8%
OTH	483	0.8%
UKIP	97	0.2%
CON Majority	9,262	15.6%

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.

Altrincham and Knutsford: Map

List of old seats forming part of Altrincham and Knutsford

Old seat: Altrincham and Sale West

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

Old seat: Altrincham and Sale West				Transfer-adjusted Results
District	Ward	Electorate 2017	New Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	NAT Votes	MIN Votes	OTH Votes	Total Votes
Trafford	Altrincham	8,160	Altrincham and Knutsford	3,145	2,398	536	0	138	0	0	33	6,250
Trafford	Ashton upon Mersey	7,140	Stretford and Urmston	2,510	2,227	340	0	105	0	0	31	5,213
Trafford	Bowdon	7,073	Altrincham and Knutsford	3,291	1,455	281	0	92	0	0	30	5,149
Trafford	Broadheath	9,336	Altrincham and Knutsford	3,095	3,237	469	0	114	0	0	34	6,949
Trafford	Hale Barns	7,132	Altrincham and Knutsford	3,303	1,575	307	0	87	0	0	37	5,309
Trafford	Hale Central	7,084	Altrincham and Knutsford	3,173	1,804	413	0	116	0	0	25	5,531
Trafford	St Mary's	8,060	Stretford and Urmston	2,973	3,044	347	0	124	0	0	40	6,528
Trafford	Timperley	8,267	Altrincham and Knutsford	2,947	2,160	739	0	117	0	0	34	5,997
Trafford	Village	7,467	Altrincham and Knutsford	2,496	2,607	618	0	107	0	0	35	5,863
	Total	69,719		26,933	20,507	4,050	0	1,000	0	0	299	52,789

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

Old seat: Stretford and Urmston

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

Old seat: Stretford and Urmston				Transfer-adjusted Results
District	Ward	Electorate 2017	New Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	NAT Votes	MIN Votes	OTH Votes	Total Votes
Trafford	Bucklow-St Martins	6,520	Altrincham and Knutsford	1,316	3,835	43	97	55	0	0	14	5,360
Trafford	Clifford	7,004	Stretford and Urmston	637	5,036	73	59	96	0	0	11	5,912
Trafford	Davyhulme East	7,358	Stretford and Urmston	1,915	2,839	88	239	60	0	0	10	5,151
Trafford	Davyhulme West	7,413	Stretford and Urmston	2,107	2,611	62	88	52	0	0	13	4,933
Trafford	Flixton	8,051	Stretford and Urmston	2,172	2,890	175	91	63	0	0	20	5,411
Trafford	Gorse Hill	7,454	Stretford and Urmston	1,302	4,418	90	103	77	0	0	13	6,003
Trafford	Longford	8,217	Stretford and Urmston	1,219	4,811	105	74	93	0	0	16	6,318
Trafford	Stretford	7,300	Stretford and Urmston	1,248	3,925	185	88	72	0	0	13	5,531
Trafford	Urmston	8,107	Stretford and Urmston	1,899	3,154	181	255	72	0	0	11	5,572
	Total	67,424		13,815	33,519	1,002	1,094	640	0	0	121	50,191

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

Old seat: Tatton

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

Old seat: Tatton				Transfer-adjusted Results
District	Ward	Electorate 2017	New Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	NAT Votes	MIN Votes	OTH Votes	Total Votes
Cheshire East	Alderley Edge	3,425	Bramhall and Wilmslow	1,746	654	256	0	43	0	0	78	2,777
Cheshire East	Chelford	3,169	Macclesfield	1,577	406	269	0	65	0	0	32	2,349
Cheshire East	Handforth	6,709	Bramhall and Wilmslow	2,517	2,030	507	0	87	0	0	146	5,287
Cheshire East	High Legh	3,349	Altrincham and Knutsford	1,807	469	156	0	78	0	0	22	2,532
Cheshire East	Knutsford	9,902	Altrincham and Knutsford	4,888	1,895	616	0	109	0	0	173	7,681
Cheshire East	Mobberley	3,357	Altrincham and Knutsford	1,705	469	407	0	28	0	0	46	2,655
Cheshire East	Wilmslow Dean Row	3,294	Bramhall and Wilmslow	1,609	657	223	0	40	0	0	65	2,594
Cheshire East	Wilmslow East	2,880	Bramhall and Wilmslow	1,523	492	200	0	92	0	0	59	2,366
Cheshire East	Wilmslow Lacey Green	3,304	Bramhall and Wilmslow	1,559	1,037	209	0	40	0	0	25	2,870
Cheshire East	Wilmslow West and Chorley	7,442	Bramhall and Wilmslow	3,566	1,342	493	0	196	0	0	117	5,714
Cheshire West and Chester	Marbury	9,496	Weaver Vale	3,775	2,348	632	0	187	0	0	90	7,032
Cheshire West and Chester	Shakerley	3,431	Eddisbury	1,433	710	227	0	27	0	0	36	2,433
Cheshire West and Chester	Witton and Rudheath	3,582	Eddisbury	1,060	1,468	238	0	31	0	0	30	2,827
	Total	63,340		28,765	13,977	4,433	0	1,023	0	0	919	49,117

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

New seat: Altrincham and Knutsford

District	Ward	Electorate 2017	Old Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	NAT Votes	MIN Votes	OTH Votes	Total Votes
New seat: Altrincham and Knutsford
Cheshire East	High Legh	3,500	Tatton	1,807	469	156	0	78	0	0	22	2,532
Cheshire East	Knutsford	10,614	Tatton	4,888	1,895	616	0	109	0	0	173	7,681
Cheshire East	Mobberley	3,670	Tatton	1,705	469	407	0	28	0	0	46	2,655
Trafford	Altrincham	8,669	Altrincham and Sale West	3,145	2,398	536	0	138	0	0	33	6,250
Trafford	Bowdon	7,142	Altrincham and Sale West	3,291	1,455	281	0	92	0	0	30	5,149
Trafford	Broadheath	9,638	Altrincham and Sale West	3,095	3,237	469	0	114	0	0	34	6,949
Trafford	Bucklow-St Martins	7,673	Stretford and Urmston	1,316	3,835	43	97	55	0	0	14	5,360
Trafford	Hale Barns	7,365	Altrincham and Sale West	3,303	1,575	307	0	87	0	0	37	5,309
Trafford	Hale Central	7,671	Altrincham and Sale West	3,173	1,804	413	0	116	0	0	25	5,531
Trafford	Timperley	8,319	Altrincham and Sale West	2,947	2,160	739	0	117	0	0	34	5,997
Trafford	Village	8,131	Altrincham and Sale West	2,496	2,607	618	0	107	0	0	35	5,863
	Total	82,392		31,166	21,904	4,585	97	1,041	0	0	483	59,276

And these are the implied results for 2017 for the new seat of Altrincham and Knutsford. Please note that the wards used are those of 2015 in order to be consistent with those used by the Boundary Commissions.

Implied MP at 2017:	Graham Brady (CON)
County/Area:	Central Manchester (North West)
Electorate:	82,392
Turnout:	71.9%

Altrincham and Knutsford: New Boundaries 2018 Calculation

Altrincham and Knutsford: Overview

Introduction