New Seat Details - Brecon, Radnor and Montgomery

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Brecon, Radnor and Montgomery 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	28,864	49.5%
LIB	16,219	27.8%
LAB	10,099	17.3%
Plaid	2,245	3.9%
UKIP	579	1.0%
Green	253	0.4%
CON Majority	12,645	21.7%

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.

Brecon, Radnor and Montgomery: Map

List of old seats forming part of Brecon, Radnor and Montgomery

Old seat: Brecon and Radnorshire

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

Old seat: Brecon and Radnorshire				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
Powys	Aber-craf	1,074	Brecon, Radnor and Montgomery	337	295	183	14	0	21	0	0	850
Powys	Beguildy	1,102	Brecon, Radnor and Montgomery	467	122	217	14	0	52	0	0	872
Powys	Bronllys	950	Brecon, Radnor and Montgomery	438	88	187	11	0	27	0	0	751
Powys	Builth	1,942	Brecon, Radnor and Montgomery	633	220	614	21	0	48	0	0	1,536
Powys	Bwlch	720	Brecon, Radnor and Montgomery	267	39	240	5	0	18	0	0	569
Powys	Crickhowell	2,195	Brecon, Radnor and Montgomery	750	169	761	21	0	36	0	0	1,737
Powys	Cwm-twrch	1,544	Brecon, Radnor and Montgomery	490	438	247	21	0	25	0	0	1,221
Powys	Disserth and Trecoed	957	Brecon, Radnor and Montgomery	409	98	228	11	0	12	0	0	758
Powys	Felin-fâch	1,028	Brecon, Radnor and Montgomery	517	91	164	11	0	30	0	0	813
Powys	Glasbury	1,722	Brecon, Radnor and Montgomery	916	110	269	15	0	52	0	0	1,362
Powys	Gwernyfed	1,159	Brecon, Radnor and Montgomery	582	93	188	11	0	43	0	0	917
Powys	Hay	1,217	Brecon, Radnor and Montgomery	601	116	193	11	0	43	0	0	964
Powys	Knighton	2,283	Brecon, Radnor and Montgomery	812	250	649	26	0	68	0	0	1,805
Powys	Llanafanfawr	1,043	Brecon, Radnor and Montgomery	490	81	206	11	0	37	0	0	825
Powys	Llanbadarn Fawr	862	Brecon, Radnor and Montgomery	391	91	168	10	0	21	0	0	681
Powys	Llandrindod East / Llandrindod West	930	Brecon, Radnor and Montgomery	300	116	296	10	0	13	0	0	735
Powys	Llandrindod North	1,540	Brecon, Radnor and Montgomery	601	271	288	22	0	35	0	0	1,217
Powys	Llandrindod South	1,521	Brecon, Radnor and Montgomery	621	167	377	18	0	20	0	0	1,203
Powys	Llanelwedd	893	Brecon, Radnor and Montgomery	304	61	304	8	0	30	0	0	707
Powys	Llangattock	759	Brecon, Radnor and Montgomery	299	61	219	7	0	14	0	0	600
Powys	Llangors	809	Brecon, Radnor and Montgomery	321	53	240	7	0	18	0	0	639
Powys	Llangunllo	923	Brecon, Radnor and Montgomery	420	83	184	9	0	34	0	0	730
Powys	Llangynidr	775	Brecon, Radnor and Montgomery	349	55	187	7	0	14	0	0	612
Powys	Llanwrtyd Wells	1,410	Brecon, Radnor and Montgomery	520	140	387	15	0	53	0	0	1,115
Powys	Llanyre	858	Brecon, Radnor and Montgomery	397	81	172	11	0	16	0	0	677
Powys	Maescar / Llywel	1,298	Brecon, Radnor and Montgomery	596	127	241	16	0	47	0	0	1,027
Powys	Nantmel	1,129	Brecon, Radnor and Montgomery	576	91	185	11	0	29	0	0	892
Powys	Old Radnor	1,191	Brecon, Radnor and Montgomery	448	85	364	11	0	33	0	0	941
Powys	Presteigne	2,049	Brecon, Radnor and Montgomery	803	225	517	24	0	52	0	0	1,621
Powys	Rhayader	1,565	Brecon, Radnor and Montgomery	490	229	476	16	0	27	0	0	1,238
Powys	St David Within	1,354	Brecon, Radnor and Montgomery	425	380	223	17	0	27	0	0	1,072
Powys	St John	2,518	Brecon, Radnor and Montgomery	739	716	443	30	0	63	0	0	1,991
Powys	St Mary	2,353	Brecon, Radnor and Montgomery	783	388	604	25	0	60	0	0	1,860
Powys	Talgarth	1,279	Brecon, Radnor and Montgomery	403	114	441	13	0	39	0	0	1,010
Powys	Talybont-on-Usk	1,463	Brecon, Radnor and Montgomery	686	109	308	15	0	40	0	0	1,158
Powys	Tawe-Uchaf	1,604	Brecon, Radnor and Montgomery	549	418	256	20	0	27	0	0	1,270
Powys	Ynyscedwyn	1,483	Brecon, Radnor and Montgomery	487	403	241	21	0	21	0	0	1,173
Powys	Yscir	763	Brecon, Radnor and Montgomery	283	48	245	6	0	22	0	0	604
Powys	Ystradgynlais	2,007	Brecon, Radnor and Montgomery	585	613	331	27	0	32	0	0	1,588
	Total	52,272		20,085	7,335	12,043	579	0	1,299	0	0	41,341

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

Old seat: Montgomeryshire

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

Old seat: Montgomeryshire				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
Powys	Banwy	746	Clwyd South and North Montgomeryshire	286	84	129	0	10	36	0	0	545
Powys	Berriew	1,064	Clwyd South and North Montgomeryshire	420	99	174	0	11	49	0	0	753
Powys	Blaen Hafren	1,782	Brecon, Radnor and Montgomery	848	136	220	0	18	66	0	0	1,288
Powys	Caersws	1,712	Brecon, Radnor and Montgomery	720	190	277	0	20	72	0	0	1,279
Powys	Churchstoke	1,214	Brecon, Radnor and Montgomery	373	97	349	0	12	42	0	0	873
Powys	Dolforwyn	1,587	Brecon, Radnor and Montgomery	636	145	227	0	15	59	0	0	1,082
Powys	Forden	1,083	Brecon, Radnor and Montgomery	509	89	150	0	10	34	0	0	792
Powys	Glantwymyn	1,558	Ceredigion and North Pembrokeshire	577	169	268	0	19	82	0	0	1,115
Powys	Guilsfield	1,799	Clwyd South and North Montgomeryshire	688	182	306	0	21	77	0	0	1,274
Powys	Kerry	1,563	Brecon, Radnor and Montgomery	676	140	224	0	15	69	0	0	1,124
Powys	Llanbrynmair	742	Ceredigion and North Pembrokeshire	265	81	116	0	8	31	0	0	501
Powys	Llandinam	1,063	Brecon, Radnor and Montgomery	412	110	182	0	13	52	0	0	769
Powys	Llandrinio	1,656	Clwyd South and North Montgomeryshire	658	173	274	0	16	65	0	0	1,186
Powys	Llandysilio	1,387	Clwyd South and North Montgomeryshire	527	146	225	0	13	50	0	0	961
Powys	Llanfair Caereinion	1,227	Clwyd South and North Montgomeryshire	462	139	312	0	14	60	0	0	987
Powys	Llanfihangel	872	Clwyd South and North Montgomeryshire	337	78	132	0	8	31	0	0	586
Powys	Llanfyllin	1,147	Clwyd South and North Montgomeryshire	500	122	155	0	13	49	0	0	839
Powys	Llanidloes	2,070	Brecon, Radnor and Montgomery	806	277	372	0	29	91	0	0	1,575
Powys	Llanrhaeadr-ym-Mochnant / Llansilin	1,733	Clwyd South and North Montgomeryshire	786	130	210	0	16	77	0	0	1,219
Powys	Llansantffraid	1,511	Clwyd South and North Montgomeryshire	677	124	198	0	14	44	0	0	1,057
Powys	Llanwddyn	818	Clwyd South and North Montgomeryshire	301	86	130	0	9	42	0	0	568
Powys	Machynlleth	1,627	Ceredigion and North Pembrokeshire	546	266	313	0	26	76	0	0	1,227
Powys	Meifod	1,040	Clwyd South and North Montgomeryshire	396	101	161	0	11	50	0	0	719
Powys	Montgomery	1,059	Brecon, Radnor and Montgomery	408	111	179	0	13	42	0	0	753
Powys	Newtown Central	2,103	Brecon, Radnor and Montgomery	996	380	331	0	26	66	0	0	1,799
Powys	Newtown East	1,391	Brecon, Radnor and Montgomery	321	211	438	0	17	139	0	0	1,126
Powys	Newtown Llanllwchaiarn North	1,726	Brecon, Radnor and Montgomery	458	170	532	0	18	58	0	0	1,236
Powys	Newtown Llanllwchaiarn West	1,361	Brecon, Radnor and Montgomery	614	134	188	0	14	40	0	0	990
Powys	Newtown South	1,242	Brecon, Radnor and Montgomery	344	403	233	0	16	40	0	0	1,036
Powys	Rhiwcynon	1,674	Brecon, Radnor and Montgomery	658	171	274	0	17	76	0	0	1,196
Powys	Trewern	1,054	Clwyd South and North Montgomeryshire	450	109	170	0	10	37	0	0	776
Powys	Welshpool Castle	954	Clwyd South and North Montgomeryshire	389	210	201	0	14	45	0	0	859
Powys	Welshpool Gungrog	1,772	Clwyd South and North Montgomeryshire	570	280	614	0	20	64	0	0	1,548
Powys	Welshpool Llanerchyddol	1,652	Clwyd South and North Montgomeryshire	457	201	526	0	17	49	0	0	1,250
	Total	46,989		18,071	5,544	8,790	0	523	1,960	0	0	34,888

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

New seat: Brecon, Radnor and Montgomery

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: Brecon, Radnor and Montgomery
Powys	Aber-craf	1,151	Brecon and Radnorshire	337	295	183	14	0	21	0	0	850
Powys	Beguildy	1,181	Brecon and Radnorshire	467	122	217	14	0	52	0	0	872
Powys	Blaen Hafren	1,873	Montgomeryshire	848	136	220	0	18	66	0	0	1,288
Powys	Bronllys	1,018	Brecon and Radnorshire	438	88	187	11	0	27	0	0	751
Powys	Builth	2,081	Brecon and Radnorshire	633	220	614	21	0	48	0	0	1,536
Powys	Bwlch	771	Brecon and Radnorshire	267	39	240	5	0	18	0	0	569
Powys	Caersws	1,860	Montgomeryshire	720	190	277	0	20	72	0	0	1,279
Powys	Churchstoke	1,268	Montgomeryshire	373	97	349	0	12	42	0	0	873
Powys	Crickhowell	2,352	Brecon and Radnorshire	750	169	761	21	0	36	0	0	1,737
Powys	Cwm-twrch	1,654	Brecon and Radnorshire	490	438	247	21	0	25	0	0	1,221
Powys	Disserth and Trecoed	1,025	Brecon and Radnorshire	409	98	228	11	0	12	0	0	758
Powys	Dolforwyn	1,574	Montgomeryshire	636	145	227	0	15	59	0	0	1,082
Powys	Felin-fâch	1,101	Brecon and Radnorshire	517	91	164	11	0	30	0	0	813
Powys	Forden	1,152	Montgomeryshire	509	89	150	0	10	34	0	0	792
Powys	Glasbury	1,845	Brecon and Radnorshire	916	110	269	15	0	52	0	0	1,362
Powys	Gwernyfed	1,242	Brecon and Radnorshire	582	93	188	11	0	43	0	0	917
Powys	Hay	1,304	Brecon and Radnorshire	601	116	193	11	0	43	0	0	964
Powys	Kerry	1,636	Montgomeryshire	676	140	224	0	15	69	0	0	1,124
Powys	Knighton	2,446	Brecon and Radnorshire	812	250	649	26	0	68	0	0	1,805
Powys	Llanafanfawr	1,118	Brecon and Radnorshire	490	81	206	11	0	37	0	0	825
Powys	Llanbadarn Fawr	924	Brecon and Radnorshire	391	91	168	10	0	21	0	0	681
Powys	Llandinam	1,118	Montgomeryshire	412	110	182	0	13	52	0	0	769
Powys	Llandrindod East / Llandrindod West	996	Brecon and Radnorshire	300	116	296	10	0	13	0	0	735
Powys	Llandrindod North	1,650	Brecon and Radnorshire	601	271	288	22	0	35	0	0	1,217
Powys	Llandrindod South	1,630	Brecon and Radnorshire	621	167	377	18	0	20	0	0	1,203
Powys	Llanelwedd	957	Brecon and Radnorshire	304	61	304	8	0	30	0	0	707
Powys	Llangattock	813	Brecon and Radnorshire	299	61	219	7	0	14	0	0	600
Powys	Llangors	867	Brecon and Radnorshire	321	53	240	7	0	18	0	0	639
Powys	Llangunllo	989	Brecon and Radnorshire	420	83	184	9	0	34	0	0	730
Powys	Llangynidr	830	Brecon and Radnorshire	349	55	187	7	0	14	0	0	612
Powys	Llanidloes	2,292	Montgomeryshire	806	277	372	0	29	91	0	0	1,575
Powys	Llanwrtyd Wells	1,511	Brecon and Radnorshire	520	140	387	15	0	53	0	0	1,115
Powys	Llanyre	919	Brecon and Radnorshire	397	81	172	11	0	16	0	0	677
Powys	Maescar / Llywel	1,391	Brecon and Radnorshire	596	127	241	16	0	47	0	0	1,027
Powys	Montgomery	1,095	Montgomeryshire	408	111	179	0	13	42	0	0	753
Powys	Nantmel	1,210	Brecon and Radnorshire	576	91	185	11	0	29	0	0	892
Powys	Newtown Central	2,618	Montgomeryshire	996	380	331	0	26	66	0	0	1,799
Powys	Newtown East	1,639	Montgomeryshire	321	211	438	0	17	139	0	0	1,126
Powys	Newtown Llanllwchaiarn North	1,798	Montgomeryshire	458	170	532	0	18	58	0	0	1,236
Powys	Newtown Llanllwchaiarn West	1,441	Montgomeryshire	614	134	188	0	14	40	0	0	990
Powys	Newtown South	1,507	Montgomeryshire	344	403	233	0	16	40	0	0	1,036
Powys	Old Radnor	1,276	Brecon and Radnorshire	448	85	364	11	0	33	0	0	941
Powys	Presteigne	2,196	Brecon and Radnorshire	803	225	517	24	0	52	0	0	1,621
Powys	Rhayader	1,677	Brecon and Radnorshire	490	229	476	16	0	27	0	0	1,238
Powys	Rhiwcynon	1,741	Montgomeryshire	658	171	274	0	17	76	0	0	1,196
Powys	St David Within	1,451	Brecon and Radnorshire	425	380	223	17	0	27	0	0	1,072
Powys	St John	2,698	Brecon and Radnorshire	739	716	443	30	0	63	0	0	1,991
Powys	St Mary	2,521	Brecon and Radnorshire	783	388	604	25	0	60	0	0	1,860
Powys	Talgarth	1,370	Brecon and Radnorshire	403	114	441	13	0	39	0	0	1,010
Powys	Talybont-on-Usk	1,568	Brecon and Radnorshire	686	109	308	15	0	40	0	0	1,158
Powys	Tawe-Uchaf	1,719	Brecon and Radnorshire	549	418	256	20	0	27	0	0	1,270
Powys	Ynyscedwyn	1,589	Brecon and Radnorshire	487	403	241	21	0	21	0	0	1,173
Powys	Yscir	818	Brecon and Radnorshire	283	48	245	6	0	22	0	0	604
Powys	Ystradgynlais	2,151	Brecon and Radnorshire	585	613	331	27	0	32	0	0	1,588
	Total	80,622		28,864	10,099	16,219	579	253	2,245	0	0	58,259

And these are the implied results for 2017 for the new seat of Brecon, Radnor and Montgomery. 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:	Chris Davies (CON)
County/Area:	Powys (Wales)
Electorate:	80,622
Turnout:	72.3%

Brecon, Radnor and Montgomery: New Boundaries 2018 Calculation

Brecon, Radnor and Montgomery: Overview

Introduction