New Seat Details - Bridgend and Vale of Glamorgan West

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Bridgend and Vale of Glamorgan 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
LAB	26,566	48.1%
CON	23,571	42.7%
Plaid	2,188	4.0%
LIB	1,084	2.0%
UKIP	976	1.8%
OTH	741	1.3%
Green	89	0.2%
LAB Majority	2,995	5.4%

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.

Bridgend and Vale of Glamorgan West: Map

List of old seats forming part of Bridgend and Vale of Glamorgan West

Old seat: Bridgend

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

Old seat: Bridgend				Transfer-adjusted Results
District	Ward	Electorate 2017	New Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	Plaid Votes	MIN Votes	OTH Votes	Total Votes
Bridgend	Brackla	8,577	Bridgend and Vale of Glamorgan West	2,095	3,439	162	108	0	400	0	90	6,294
Bridgend	Bryntirion, Laleston and Merthyrmawr	6,519	Bridgend and Vale of Glamorgan West	1,970	2,394	161	77	0	149	0	34	4,785
Bridgend	Cefn Glas	1,036	Bridgend and Vale of Glamorgan West	266	429	20	15	0	20	0	10	760
Bridgend	Coity	1,540	Bridgend and Vale of Glamorgan West	596	399	52	27	0	24	0	34	1,132
Bridgend	Cornelly	5,204	Bridgend and Vale of Glamorgan West	1,388	2,146	38	74	0	90	0	84	3,820
Bridgend	Coychurch Lower	1,018	Bridgend and Vale of Glamorgan West	382	316	4	16	0	12	0	17	747
Bridgend	Litchard	1,586	Bridgend and Vale of Glamorgan West	538	557	13	19	0	29	0	8	1,164
Bridgend	Llangewydd and Brynhyfryd	1,984	Bridgend and Vale of Glamorgan West	443	860	47	26	0	58	0	21	1,455
Bridgend	Morfa	3,448	Bridgend and Vale of Glamorgan West	793	1,392	37	49	0	206	0	53	2,530
Bridgend	Newcastle	3,949	Bridgend and Vale of Glamorgan West	1,168	1,555	33	46	0	72	0	24	2,898
Bridgend	Newton	2,667	Bridgend and Vale of Glamorgan West	1,097	660	18	32	0	130	0	20	1,957
Bridgend	Nottage	2,492	Bridgend and Vale of Glamorgan West	926	755	57	36	0	41	0	14	1,829
Bridgend	Oldcastle	3,554	Bridgend and Vale of Glamorgan West	1,033	1,287	62	48	0	137	0	42	2,609
Bridgend	Pen-y-fai	1,790	Bridgend and Vale of Glamorgan West	662	557	11	22	0	39	0	22	1,313
Bridgend	Pendre	1,439	Bridgend and Vale of Glamorgan West	367	560	32	20	0	69	0	8	1,056
Bridgend	Porthcawl East Central	2,498	Bridgend and Vale of Glamorgan West	691	919	19	35	0	134	0	34	1,832
Bridgend	Porthcawl West Central	2,546	Bridgend and Vale of Glamorgan West	870	836	27	37	0	46	0	53	1,869
Bridgend	Pyle	5,474	Bridgend and Vale of Glamorgan West	1,205	2,477	99	72	0	105	0	60	4,018
Bridgend	Rest Bay	1,613	Bridgend and Vale of Glamorgan West	722	374	27	21	0	21	0	18	1,183
	Total	58,934		17,212	21,912	919	780	0	1,782	0	646	43,251

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

Old seat: Ogmore

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

Old seat: Ogmore				Transfer-adjusted Results
District	Ward	Electorate 2017	New Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	Plaid Votes	MIN Votes	OTH Votes	Total Votes
Bridgend	Aberkenfig	1,692	Ogmore and Aberavon	289	494	17	38	0	172	0	0	1,010
Bridgend	Bettws (Ogmore)	1,536	Ogmore and Aberavon	215	815	8	33	0	38	0	0	1,109
Bridgend	Blackmill	1,870	Ogmore and Aberavon	279	857	12	36	0	53	0	0	1,237
Bridgend	Blaengarw	1,260	Ogmore and Aberavon	187	619	17	29	0	40	0	0	892
Bridgend	Bryncethin	995	Ogmore and Aberavon	162	413	26	20	0	44	0	0	665
Bridgend	Bryncoch	1,652	Ogmore and Aberavon	264	738	34	34	0	49	0	0	1,119
Bridgend	Caerau	4,593	Ogmore and Aberavon	726	2,492	29	121	0	117	0	0	3,485
Bridgend	Cefn Cribwr	1,088	Bridgend and Vale of Glamorgan West	186	483	5	23	0	42	0	0	739
Bridgend	Felindre	2,046	Ogmore and Aberavon	402	822	51	43	0	63	0	0	1,381
Bridgend	Hendre	2,985	Ogmore and Aberavon	631	1,243	21	64	0	98	0	0	2,057
Bridgend	Llangeinor	846	Ogmore and Aberavon	151	418	4	19	0	28	0	0	620
Bridgend	Llangynwyd	2,330	Ogmore and Aberavon	445	788	16	54	0	214	0	0	1,517
Bridgend	Maesteg East	3,536	Ogmore and Aberavon	564	1,506	18	84	0	206	0	0	2,378
Bridgend	Maesteg West	4,185	Ogmore and Aberavon	684	1,700	90	100	0	316	0	0	2,890
Bridgend	Nant-y-moel	1,657	Ogmore and Aberavon	297	756	19	42	0	53	0	0	1,167
Bridgend	Ogmore Vale	2,193	Ogmore and Aberavon	394	982	36	54	0	88	0	0	1,554
Bridgend	Penprysg	2,337	Ogmore and Aberavon	443	949	24	49	0	100	0	0	1,565
Bridgend	Pontycymmer	1,648	Ogmore and Aberavon	256	876	19	42	0	52	0	0	1,245
Bridgend	Sarn	1,748	Ogmore and Aberavon	270	840	16	38	0	54	0	0	1,218
Bridgend	Ynysawdre	2,555	Ogmore and Aberavon	460	935	21	57	0	209	0	0	1,682
Rhondda Cynon Taf	Brynna	3,264	Ogmore and Aberavon	522	1,075	18	61	0	228	0	0	1,904
Rhondda Cynon Taf	Gilfach Goch	2,411	Ogmore and Aberavon	366	1,196	48	52	0	62	0	0	1,724
Rhondda Cynon Taf	Llanharan	2,610	Ogmore and Aberavon	498	966	15	55	0	194	0	0	1,728
Rhondda Cynon Taf	Llanharry	2,940	Rhondda and Llantrisant	491	1,070	25	58	0	203	0	0	1,847
Rhondda Cynon Taf	Pont-y-clun	707	Rhondda and Llantrisant	168	190	6	29	0	71	0	0	464
Rhondda Cynon Taf	Talbot Green	12	Rhondda and Llantrisant	2	4	0	0	0	1	0	0	7
	Total	54,696		9,352	23,227	595	1,235	0	2,795	0	0	37,204

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

Old seat: Vale of Glamorgan

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

Old seat: Vale of Glamorgan				Transfer-adjusted Results
District	Ward	Electorate 2017	New Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	Plaid Votes	MIN Votes	OTH Votes	Total Votes
Vale of Glamorgan	Baruc	4,636	Vale of Glamorgan East	1,671	1,375	99	77	38	239	0	25	3,524
Vale of Glamorgan	Buttrills	4,175	Vale of Glamorgan East	1,232	1,959	92	64	34	182	0	19	3,582
Vale of Glamorgan	Cadoc	6,842	Vale of Glamorgan East	1,891	3,061	114	97	38	278	0	28	5,507
Vale of Glamorgan	Castleland	3,096	Vale of Glamorgan East	822	1,555	65	44	27	124	0	6	2,643
Vale of Glamorgan	Court	3,031	Vale of Glamorgan East	848	1,531	61	50	25	111	0	14	2,640
Vale of Glamorgan	Cowbridge	4,997	Vale of Glamorgan East	2,206	936	46	39	21	131	0	23	3,402
Vale of Glamorgan	Dinas Powys	6,139	Vale of Glamorgan East	2,433	1,399	103	79	36	249	0	12	4,311
Vale of Glamorgan	Dyfan	3,983	Vale of Glamorgan East	1,198	1,376	53	44	22	118	0	7	2,818
Vale of Glamorgan	Gibbonsdown	3,646	Vale of Glamorgan East	978	1,962	49	48	24	103	0	16	3,180
Vale of Glamorgan	Illtyd	5,951	Vale of Glamorgan East	1,923	2,008	107	81	37	241	0	29	4,426
Vale of Glamorgan	Llandow / Ewenny	2,061	Bridgend and Vale of Glamorgan West	960	382	18	19	8	76	0	3	1,466
Vale of Glamorgan	Llantwit Major	7,502	Bridgend and Vale of Glamorgan West	2,990	2,358	110	107	45	160	0	48	5,818
Vale of Glamorgan	Peterston-super-Ely	1,828	Vale of Glamorgan East	867	320	7	10	4	23	0	5	1,236
Vale of Glamorgan	Rhoose	5,158	Vale of Glamorgan East	2,285	1,280	50	52	20	106	0	22	3,815
Vale of Glamorgan	St Athan	2,412	Bridgend and Vale of Glamorgan West	1,318	968	18	32	11	92	0	36	2,475
Vale of Glamorgan	St Bride's Major	2,097	Bridgend and Vale of Glamorgan West	905	463	14	15	25	36	0	8	1,466
Vale of Glamorgan	Wenvoe	2,122	Vale of Glamorgan East	972	380	12	13	6	27	0	2	1,412
	Total	69,676		25,499	23,313	1,018	871	421	2,296	0	303	53,721

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

New seat: Bridgend and Vale of Glamorgan West

District	Ward	Electorate 2017	Old Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	Plaid Votes	MIN Votes	OTH Votes	Total Votes
New seat: Bridgend and Vale of Glamorgan West
Bridgend	Brackla	9,050	Bridgend	2,095	3,439	162	108	0	400	0	90	6,294
Bridgend	Bryntirion, Laleston and Merthyrmawr	6,879	Bridgend	1,970	2,394	161	77	0	149	0	34	4,785
Bridgend	Cefn Cribwr	1,126	Ogmore	186	483	5	23	0	42	0	0	739
Bridgend	Cefn Glas	1,093	Bridgend	266	429	20	15	0	20	0	10	760
Bridgend	Coity	1,625	Bridgend	596	399	52	27	0	24	0	34	1,132
Bridgend	Cornelly	5,491	Bridgend	1,388	2,146	38	74	0	90	0	84	3,820
Bridgend	Coychurch Lower	1,074	Bridgend	382	316	4	16	0	12	0	17	747
Bridgend	Litchard	1,673	Bridgend	538	557	13	19	0	29	0	8	1,164
Bridgend	Llangewydd and Brynhyfryd	2,094	Bridgend	443	860	47	26	0	58	0	21	1,455
Bridgend	Morfa	3,638	Bridgend	793	1,392	37	49	0	206	0	53	2,530
Bridgend	Newcastle	4,167	Bridgend	1,168	1,555	33	46	0	72	0	24	2,898
Bridgend	Newton	2,814	Bridgend	1,097	660	18	32	0	130	0	20	1,957
Bridgend	Nottage	2,629	Bridgend	926	755	57	36	0	41	0	14	1,829
Bridgend	Oldcastle	3,750	Bridgend	1,033	1,287	62	48	0	137	0	42	2,609
Bridgend	Pen-y-fai	1,889	Bridgend	662	557	11	22	0	39	0	22	1,313
Bridgend	Pendre	1,518	Bridgend	367	560	32	20	0	69	0	8	1,056
Bridgend	Porthcawl East Central	2,636	Bridgend	691	919	19	35	0	134	0	34	1,832
Bridgend	Porthcawl West Central	2,686	Bridgend	870	836	27	37	0	46	0	53	1,869
Bridgend	Pyle	5,776	Bridgend	1,205	2,477	99	72	0	105	0	60	4,018
Bridgend	Rest Bay	1,702	Bridgend	722	374	27	21	0	21	0	18	1,183
Vale of Glamorgan	Llandow / Ewenny	2,018	Vale of Glamorgan	960	382	18	19	8	76	0	3	1,466
Vale of Glamorgan	Llantwit Major	8,011	Vale of Glamorgan	2,990	2,358	110	107	45	160	0	48	5,818
Vale of Glamorgan	St Athan	3,407	Vale of Glamorgan	1,318	968	18	32	11	92	0	36	2,475
Vale of Glamorgan	St Bride's Major	2,018	Vale of Glamorgan	905	463	14	15	25	36	0	8	1,466
	Total	78,764		23,571	26,566	1,084	976	89	2,188	0	741	55,215

And these are the implied results for 2017 for the new seat of Bridgend and Vale of Glamorgan 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:	Madeleine Moon (LAB)
County/Area:	Mid Glamorgan (Wales)
Electorate:	78,764
Turnout:	70.1%

Bridgend and Vale of Glamorgan West: New Boundaries 2018 Calculation

Bridgend and Vale of Glamorgan West: Overview

Introduction