The Britain Elects Nowcast

Updated: 04 June, 2017

Our nowcast is not a picture of what will happen on polling day but rather a snapshot as to how the nation would vote if the election were held today.

Our model, combining historical data as well as national and regional polling, estimates the probability a party has at holding onto each seat. This forecast is theoretical and does not consider targeting. Regional variation and parliamentary by-election results are, however, accounted for.

The nowcast will be updated over time.

The Nowcast

Based on current polling, we expect the composition of the House of Commons to be thus:

-	Party	Seats	+/-	Vote %	% +/-
Con	Conservative	354	24	44.3	6.5
Lab	Labour	214	-18	35.1	3.9
SNP	Scottish National	47	-9	-	-
LDem	Liberal Democrat	12	4	8.3	0.2
PC	Plaid Cymru	3	0	-	-
Grn	Green	1	0	2.0	-1.8
Oth	Independents / Other	19	0	5.8	-0.4
UKIP	UKIP	0	-1	4.5	-8.4

Seats likely to change hands

Based on current polling, of the 136 seats we expect are at risk of changing hands, 36 will more likely than not (probability >50%) do so. Mapped below are the constituencies where the probability of it changing hands exceeds 50%, coloured according to the expected winning party.

Table: Probability (by %) of seats changing hands

The table below displays the seats we think are at risk of changing hands, however small.

For those using mobile devices, the table is horizontal scrollable.

Constituency	2015	Nowcast	Probability
Clacton	UKIP	Con	100.0%
Copeland	Lab	Con	98.6%
Berwickshire, Roxburgh and Selkirk	SNP	Con	97.8%
West Aberdeenshire and Kincardine	SNP	Con	97.8%
Dumfries and Galloway	SNP	Con	96.9%
Bishop Auckland	Lab	Con	94.1%
Barrow and Furness	Lab	Con	94.0%
Darlington	Lab	Con	93.7%
Wirral West	Lab	Con	92.4%
City of Chester	Lab	Con	92.3%
Newcastle-under-Lyme	Lab	Con	92.3%
Southport	LDem	Con	92.2%
Wolverhampton South West	Lab	Con	91.4%
Lancaster and Fleetwood	Lab	Con	91.2%
Middlesbrough South and East Cleveland	Lab	Con	89.0%
North East Derbyshire	Lab	Con	83.0%
East Renfrewshire	SNP	Con	80.8%
Twickenham	Con	LDem	80.4%
Halifax	Lab	Con	78.5%
East Dunbartonshire	SNP	LDem	75.6%
Perth and North Perthshire	SNP	Con	72.5%
Walsall North	Lab	Con	72.4%
Aberdeen South	SNP	Con	70.8%
Kingston and Surbiton	Con	LDem	70.2%
Croydon Central	Con	Lab	70.0%
Birmingham, Northfield	Lab	Con	70.0%
Dewsbury	Lab	Con	69.3%
Edinburgh West	SNP	LDem	65.7%
Moray	SNP	Con	64.5%
Birmingham, Edgbaston	Lab	Con	62.0%
Bridgend	Lab	Con	60.0%
Gedling	Lab	Con	59.8%
Plymouth, Sutton and Devonport	Con	Lab	53.5%
Wrexham	Lab	Con	53.2%
Richmond Park	Con	LDem	51.4%
Stoke-on-Trent South	Lab	Con	50.3%
Coventry South	Lab	-	49.7%
Sutton and Cheam	Con	-	44.1%
Coventry North West	Lab	-	43.7%
Brighton, Kemptown	Con	-	42.4%
Sheffield, Hallam	LDem	-	41.6%
Clwyd South	Lab	-	41.4%
Cambridge	Lab	-	40.1%
Ynys Môn	Lab	-	40.1%
Plymouth, Moor View	Con	-	38.4%
Blackpool South	Lab	-	38.1%
Wakefield	Lab	-	35.4%
Edinburgh South West	SNP	-	34.5%
Leeds North West	LDem	-	34.1%
Dudley North	Lab	-	33.8%
East Lothian	SNP	-	32.9%
Scunthorpe	Lab	-	32.5%
Newport West	Lab	-	30.3%
North East Fife	SNP	-	29.0%
Alyn and Deeside	Lab	-	28.4%
Hartlepool	Lab	-	27.9%
Stirling	SNP	-	27.7%
Mansfield	Lab	-	26.6%
Delyn	Lab	-	26.1%
Edinburgh North and Leith	SNP	-	25.8%
Hyndburn	Lab	-	23.4%
Hendon	Con	-	23.1%
Eastbourne	Con	-	23.1%
Brentford and Isleworth	Lab	-	20.8%
Chorley	Lab	-	19.6%
Ealing Central and Acton	Lab	-	18.7%
Hove	Lab	-	18.6%
Tynemouth	Lab	-	18.4%
Workington	Lab	-	18.2%
Bury South	Lab	-	17.8%
Sedgefield	Lab	-	17.4%
Bolton North East	Lab	-	16.9%
Ilford North	Lab	-	16.8%
Wirral South	Lab	-	15.2%
Southampton, Itchen	Con	-	14.0%
Vale of Clwyd	Con	-	14.0%
Stoke-on-Trent North	Lab	-	13.9%
Lewes	Con	-	13.9%
Edinburgh South	Lab	-	13.7%
North Norfolk	LDem	-	13.5%
Gower	Con	-	13.4%
Enfield North	Lab	-	13.3%
Angus	SNP	-	13.3%
Bermondsey and Old Southwark	Lab	-	12.8%
Newport East	Lab	-	12.4%
Caithness, Sutherland and Easter Ross	SNP	-	12.0%
Bedford	Con	-	11.1%
Oldham East and Saddleworth	Lab	-	10.4%
Thurrock	Con	-	10.0%
Ochil and South Perthshire	SNP	-	9.6%
Hampstead and Kilburn	Lab	-	9.5%
Harrow East	Con	-	9.1%
Morley and Outwood	Con	-	9.1%
Walsall South	Lab	-	8.3%
Ellesmere Port and Neston	Lab	-	8.2%
Paisley and Renfrewshire South	SNP	-	7.9%
Batley and Spen	Lab	-	6.8%
Southampton, Test	Lab	-	6.8%
Enfield, Southgate	Con	-	6.6%
Carshalton and Wallington	LDem	-	6.4%
Harrow West	Lab	-	5.9%
Ceredigion	LDem	-	5.8%
Birmingham, Erdington	Lab	-	5.4%
Nottingham South	Lab	-	5.2%
Stroud	Con	-	5.1%
York Central	Lab	-	4.6%
Worsley and Eccles South	Lab	-	4.5%
Cardiff West	Lab	-	4.3%
Westminster North	Lab	-	4.2%
Brighton, Pavilion	Grn	-	4.0%
Cardiff South and Penarth	Lab	-	3.8%
Tooting	Lab	-	3.0%
Finchley and Golders Green	Con	-	3.0%
Ross, Skye and Lochaber	SNP	-	3.0%
Great Grimsby	Lab	-	2.9%
Peterborough	Con	-	2.5%
Luton South	Lab	-	2.4%
Wolverhampton North East	Lab	-	2.4%
Bath	Con	-	1.7%
Bristol North West	Con	-	1.6%
Leeds North East	Lab	-	1.5%
Penistone and Stocksbridge	Lab	-	1.4%
Hastings and Rye	Con	-	0.8%
Bassetlaw	Lab	-	0.8%
Eltham	Lab	-	0.7%
Stoke-on-Trent Central	Lab	-	0.7%
Burnley	Lab	-	0.6%
Stockton North	Lab	-	0.4%
Ashfield	Lab	-	0.3%
Birmingham, Selly Oak	Lab	-	0.2%
West Lancashire	Lab	-	0.2%
Newcastle upon Tyne North	Lab	-	0.2%
Norwich South	Lab	-	0.1%
Birmingham, Yardley	Lab	-	0.1%
Dagenham and Rainham	Lab	-	0.1%
Stalybridge and Hyde	Lab	-	0.1%

Methodology

The methodology combines data from our poll of polls polling model, representative surveys of the regions, constituent nations (Scotland and Wales), constituencies, parliamentary by-elections and historical results. The first layer of our model, simply, operates on a uniform national swing according to our poll of polls. The second layer involves modifications to UNS so as to account for regional variations. The third and final layer involves the randomisation of expected share changes – within the 4pt margin of error – to project whether X, Y or Z party wins a certain constituency in a given number of tests.

Example: According to polling, Party A is expected in Region X to improve upon their support by 4.8pts on the 2015 election result. Constituency Y, which is within that region, should therefore see support for that party improve by between 0.8pts and 8.8pts. The model performs a repeated number of tests in that constituency, randomising an improvement in support between those two shares. These tests determine the probability as to how likely the seat will change hands.

This model does not account for the potential concentration of resources or issues within certain constituencies. A Lib Dem focus on Vauxhall, for example, or a Plaid Cymru one on the Rhondda, will not show up in our forecast.

I am under no illusions that this model is not perfect, but nor is pure UNS perfect, or any other form of forecast for that matter, but I hope that our forecast/nowcast, regardless, serves as an extra set of numbers in snapshotting the state of public opinion for the coming general election.

Our methodology, the TL;DR version:
A uniform national swing, but, not… so, a Non Uniform National Swing? The NUNS model?

With thanks to Ipsos Mori, YouGov, TNS, Panelbase, GfK, ICM, Survation, ComRes, Opinium, ORB, BMG and Lord Ashcroft for the polling used in our model, and the British Election Study for publicly available data.

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