New Seat Details - Dorset West

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Dorset West 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	32,094	55.7%
LIB	13,396	23.3%
LAB	10,498	18.2%
Green	1,607	2.8%
CON Majority	18,698	32.5%

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.

Dorset West: Map

List of old seats forming part of Dorset West

Old seat: Dorset North

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

Old seat: Dorset North				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
East Dorset	Alderholt	2,444	Dorset Mid	1,280	311	189	0	67	0	0	0	1,847
East Dorset	Crane	2,512	Dorset Mid	1,463	254	165	0	29	0	0	0	1,911
East Dorset	Handley Vale	2,278	Dorset Mid	1,268	224	141	0	25	0	0	0	1,658
East Dorset	St Leonards	1,259	Christchurch	683	124	83	0	14	0	0	0	904
East Dorset	Stour	1,968	Dorset Mid	1,083	215	145	0	24	0	0	0	1,467
East Dorset	Verwood East	4,646	Christchurch	2,519	470	334	0	54	0	0	0	3,377
East Dorset	Verwood West	5,079	Christchurch	2,636	700	478	0	69	0	0	0	3,883
East Dorset	West Moors and Holt	1,033	Christchurch	536	130	83	0	23	0	0	0	772
North Dorset	Abbey	2,913	Dorset Mid	1,617	356	202	0	76	0	0	0	2,251
North Dorset	Blackmore	2,777	Dorset West	1,400	401	210	0	73	0	0	0	2,084
North Dorset	Blandford Central	2,999	Dorset Mid	1,145	579	583	0	101	0	0	0	2,408
North Dorset	Blandford Hilltop	1,537	Dorset Mid	699	364	137	0	44	0	0	0	1,244
North Dorset	Blandford Langton St Leonards	1,513	Dorset Mid	536	273	300	0	19	0	0	0	1,128
North Dorset	Blandford Old Town	1,318	Dorset Mid	608	231	301	0	25	0	0	0	1,165
North Dorset	Bulbarrow	1,533	Warminster and Shaftesbury	779	196	115	0	41	0	0	0	1,131
North Dorset	Gillingham Rural	3,146	Warminster and Shaftesbury	1,521	387	454	0	43	0	0	0	2,405
North Dorset	Gillingham Town	4,255	Warminster and Shaftesbury	1,734	947	804	0	124	0	0	0	3,609
North Dorset	Hill Forts	4,891	Warminster and Shaftesbury	2,653	688	382	0	138	0	0	0	3,861
North Dorset	Lower Tarrants	1,484	Dorset Mid	1,375	294	168	0	65	0	0	0	1,902
North Dorset	Lydden Vale	1,464	Dorset West	789	190	96	0	37	0	0	0	1,112
North Dorset	Motcombe and Bourton	3,131	Warminster and Shaftesbury	1,825	458	258	0	88	0	0	0	2,629
North Dorset	Riversdale and Portman	2,757	Dorset Mid	1,551	515	252	0	96	0	0	0	2,414
North Dorset	Shaftesbury East	2,867	Warminster and Shaftesbury	1,202	511	243	0	38	0	0	0	1,994
North Dorset	Shaftesbury West	2,881	Warminster and Shaftesbury	1,095	479	609	0	93	0	0	0	2,276
North Dorset	Sturminster Newton	2,987	Warminster and Shaftesbury	1,462	488	452	0	87	0	0	0	2,489
North Dorset	The Beacon	1,528	Warminster and Shaftesbury	988	176	126	0	22	0	0	0	1,312
North Dorset	The Stours and Marnhull	3,350	Warminster and Shaftesbury	1,722	431	245	0	92	0	0	0	2,490
	Total	70,550		36,169	10,392	7,555	0	1,607	0	0	0	55,723

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

Old seat: Dorset South

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

Old seat: Dorset South				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
Purbeck	Castle	1,411	Dorset South	695	248	27	0	28	0	0	0	998
Purbeck	Creech Barrow	1,475	Dorset South	727	221	28	0	26	0	0	0	1,002
Purbeck	Langton	1,281	Dorset South	603	178	25	0	49	0	0	0	855
Purbeck	Lulworth and Winfrith	1,331	Dorset South	713	241	20	0	22	0	0	0	996
Purbeck	Swanage North	3,734	Dorset South	1,635	694	139	0	104	0	0	0	2,572
Purbeck	Swanage South	3,862	Dorset South	1,618	887	181	0	166	0	0	0	2,852
Purbeck	Wool	4,503	Dorset South	2,417	907	279	0	136	0	0	0	3,739
West Dorset	Broadmayne and Crossways	2,869	Dorset South	1,287	479	157	0	94	0	0	0	2,017
West Dorset	Puddletown	190	Dorset West	93	30	10	0	7	0	0	0	140
Weymouth and Portland	Littlemoor	2,442	Dorset South	829	1,141	68	0	56	0	0	0	2,094
Weymouth and Portland	Melcombe Regis	3,979	Dorset South	1,575	1,300	249	0	198	0	0	0	3,322
Weymouth and Portland	Preston	4,213	Dorset South	1,854	608	211	0	69	0	0	0	2,742
Weymouth and Portland	Radipole	2,787	Dorset South	1,159	683	214	0	56	0	0	0	2,112
Weymouth and Portland	Tophill East	2,477	Dorset South	1,056	751	111	0	155	0	0	0	2,073
Weymouth and Portland	Tophill West	3,689	Dorset South	1,493	1,137	135	0	155	0	0	0	2,920
Weymouth and Portland	Underhill	2,573	Dorset South	1,380	704	106	0	68	0	0	0	2,258
Weymouth and Portland	Upwey and Broadwey	2,780	Dorset South	1,137	701	74	0	116	0	0	0	2,028
Weymouth and Portland	Westham East	2,610	Dorset South	925	981	202	0	62	0	0	0	2,170
Weymouth and Portland	Westham North	4,003	Dorset South	1,401	1,209	249	0	76	0	0	0	2,935
Weymouth and Portland	Westham West	2,752	Dorset South	948	848	181	0	51	0	0	0	2,028
Weymouth and Portland	Wey Valley	2,760	Dorset South	1,252	500	67	0	107	0	0	0	1,926
Weymouth and Portland	Weymouth East	2,493	Dorset South	1,136	684	82	0	148	0	0	0	2,050
Weymouth and Portland	Weymouth West	3,848	Dorset South	1,567	1,077	101	0	171	0	0	0	2,916
Weymouth and Portland	Wyke Regis	4,119	Dorset South	1,633	1,231	135	0	158	0	0	0	3,157
	Total	68,181		29,133	17,440	3,051	0	2,278	0	0	0	51,902

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

Old seat: Dorset West

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

Old seat: Dorset 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
West Dorset	Beaminster	4,101	Dorset West	1,815	505	837	0	83	0	0	0	3,240
West Dorset	Bridport North	5,784	Dorset West	2,250	1,106	1,210	0	136	0	0	0	4,702
West Dorset	Bridport South	5,133	Dorset West	1,859	951	1,109	0	130	0	0	0	4,049
West Dorset	Broadmayne and Crossways	1,332	Dorset South	564	161	236	0	26	0	0	0	987
West Dorset	Broadwindsor	2,093	Dorset West	1,043	238	270	0	42	0	0	0	1,593
West Dorset	Burton Bradstock	2,084	Dorset West	1,032	225	306	0	45	0	0	0	1,608
West Dorset	Cerne Valley	4,043	Dorset West	1,877	475	673	0	87	0	0	0	3,112
West Dorset	Chickerell and Chesil Bank	5,466	Dorset South	2,705	857	674	0	116	0	0	0	4,352
West Dorset	Chideock and Symondsbury	1,933	Dorset West	947	228	289	0	43	0	0	0	1,507
West Dorset	Dorchester East	3,614	Dorset West	1,263	675	1,053	0	95	0	0	0	3,086
West Dorset	Dorchester North	4,206	Dorset West	1,487	709	1,061	0	112	0	0	0	3,369
West Dorset	Dorchester South	3,430	Dorset West	1,115	504	904	0	80	0	0	0	2,603
West Dorset	Dorchester West	3,539	Dorset West	1,195	679	872	0	87	0	0	0	2,833
West Dorset	Frome Valley	1,865	Dorset West	1,069	164	179	0	36	0	0	0	1,448
West Dorset	Lyme Regis and Charmouth	3,920	Dorset West	1,829	524	667	0	87	0	0	0	3,107
West Dorset	Maiden Newton	2,024	Dorset West	1,057	319	225	0	45	0	0	0	1,646
West Dorset	Netherbury	2,029	Dorset West	993	221	307	0	41	0	0	0	1,562
West Dorset	Piddle Valley	2,060	Dorset West	1,114	249	202	0	38	0	0	0	1,603
West Dorset	Puddletown	1,764	Dorset West	857	247	228	0	36	0	0	0	1,368
West Dorset	Queen Thorne	1,911	Dorset West	1,096	182	194	0	39	0	0	0	1,511
West Dorset	Sherborne East	3,693	Dorset West	1,783	531	581	0	96	0	0	0	2,991
West Dorset	Sherborne West	3,067	Dorset West	1,505	481	913	0	52	0	0	0	2,951
West Dorset	Winterborne St Martin	1,874	Dorset West	933	307	211	0	43	0	0	0	1,494
West Dorset	Yetminster and Cam Vale	3,688	Dorset West	1,693	357	789	0	37	0	0	0	2,876
	Total	74,653		33,081	10,895	13,990	0	1,632	0	0	0	59,598

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

New seat: Dorset West

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: Dorset West
North Dorset	Blackmore	2,857	Dorset North	1,400	401	210	0	73	0	0	0	2,084
North Dorset	Lydden Vale	1,525	Dorset North	789	190	96	0	37	0	0	0	1,112
West Dorset	Beaminster	4,298	Dorset West	1,815	505	837	0	83	0	0	0	3,240
West Dorset	Bridport North	6,237	Dorset West	2,250	1,106	1,210	0	136	0	0	0	4,702
West Dorset	Bridport South	5,371	Dorset West	1,859	951	1,109	0	130	0	0	0	4,049
West Dorset	Broadwindsor	2,112	Dorset West	1,043	238	270	0	42	0	0	0	1,593
West Dorset	Burton Bradstock	2,132	Dorset West	1,032	225	306	0	45	0	0	0	1,608
West Dorset	Cerne Valley	4,126	Dorset West	1,877	475	673	0	87	0	0	0	3,112
West Dorset	Chideock and Symondsbury	1,998	Dorset West	947	228	289	0	43	0	0	0	1,507
West Dorset	Dorchester East	4,094	Dorset West	1,263	675	1,053	0	95	0	0	0	3,086
West Dorset	Dorchester North	4,469	Dorset West	1,487	709	1,061	0	112	0	0	0	3,369
West Dorset	Dorchester South	3,452	Dorset West	1,115	504	904	0	80	0	0	0	2,603
West Dorset	Dorchester West	3,757	Dorset West	1,195	679	872	0	87	0	0	0	2,833
West Dorset	Frome Valley	1,920	Dorset West	1,069	164	179	0	36	0	0	0	1,448
West Dorset	Lyme Regis and Charmouth	4,121	Dorset West	1,829	524	667	0	87	0	0	0	3,107
West Dorset	Maiden Newton	2,183	Dorset West	1,057	319	225	0	45	0	0	0	1,646
West Dorset	Netherbury	2,070	Dorset West	993	221	307	0	41	0	0	0	1,562
West Dorset	Piddle Valley	2,126	Dorset West	1,114	249	202	0	38	0	0	0	1,603
West Dorset	Puddletown	195	Dorset South	93	30	10	0	7	0	0	0	140
West Dorset	Puddletown	1,816	Dorset West	857	247	228	0	36	0	0	0	1,368
West Dorset	Queen Thorne	2,004	Dorset West	1,096	182	194	0	39	0	0	0	1,511
West Dorset	Sherborne East	3,966	Dorset West	1,783	531	581	0	96	0	0	0	2,991
West Dorset	Sherborne West	3,914	Dorset West	1,505	481	913	0	52	0	0	0	2,951
West Dorset	Winterborne St Martin	1,983	Dorset West	933	307	211	0	43	0	0	0	1,494
West Dorset	Yetminster and Cam Vale	3,814	Dorset West	1,693	357	789	0	37	0	0	0	2,876
	Total	76,540		32,094	10,498	13,396	0	1,607	0	0	0	57,595

And these are the implied results for 2017 for the new seat of Dorset West. 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:	Oliver Letwin (CON)
County/Area:	Dorset (South West)
Electorate:	76,540
Turnout:	75.2%

Dorset West: New Boundaries 2018 Calculation

Dorset West: Overview

Introduction