UK General Election Forecast by ElectionsETC

The Conservatives have gained a point in our polling average since Wednesday, putting them level with Labour on 34% each. (68% is the highest combined share for the two parties since September.)
As a result, the Tories’ chances of winning the most votes are up to 73% and their chances of winning the most seats are up to 75%. The probability of a Tory majority is also up slightly, but it’s still just 11%. The probability of a Labour majority is down to less than 0.5%.
A hung parliament still looks very likely, with an 89% chance. We now make David Cameron and Ed Miliband pretty much 50–50 to be Prime Minister.
Cameron would very likely have to rely on the Lib Dems though: we give the Tories just a 19% chance of being able to command a majority without them, either alone or with the DUP.
Similarly, Miliband would likely have to rely on the SNP: we give Labour just a 17% chance of being able to command a majority without them. Without either the SNP or the Lib Dems, Miliband’s chances of a majority (alone or with the DUP or with the other left-wing MPs) are just 1%.
Our central forecast is for the Conservatives to win 35% of the vote and 292 seats, ahead of Labour on 33% and 260 seats. With the Lib Dems winning 22 seats and the DUP 9, a Con-LD-DUP grouping would have exactly the required 323 in this scenario. With the SNP winning 51 seats, a Lab-SNP-LD grouping would have 333. (Our central forecast, though, like any single specific combination of seats numbers, is very unlikely.)

Date of forecast: 17 April 2015
Days till the election: 20
Inputted current average poll shares
Con: 34%
Lab: 34%
LD: 8%
UKIP: 13%
Others: 11%

Forecast GB Vote Shares (with 95% Prediction Intervals)
Con: 35% (31% – 39%)
Lab: 33% (29% – 36%)
LD: 10% (6% – 14%)
UKIP: 12% (8% – 16%)
Others: 11% (9% – 12%)

Forecast Scotland Vote Shares (with 95% Prediction Intervals)
SNP: 47% (43% – 51%)
Labour: 28% (24% – 32%)
Forecast GB Seats (with 95% Prediction Intervals)
Con: 292 (251– 335)
Lab: 260 (220 – 299)
LD: 22 (14 – 31)
SNP: 51 (42 – 57)
PC: 3 (2 – 3)
UKIP: 4
Grn: 1
(May not sum to 632 due to rounding of sums of probabilities.)
Central forecast: Con short of a majority by 31
(Criterion for majority now changed to 323 not 326, assuming Sinn Fein win 5 seats and do not take them.)
Probabilities of key outcomes
Con most votes: 73%
Lab most votes: 27%
Con most seats: 75%
Lab most seats: 25%
Hung Parliament: 89%
… with Con largest: 63%
… with Lab largest: 25%
Probabilities of predicted government outcomes:
(See here for explanations and assumptions)
Con majority: 11%
Con+DUP: 8%
Con+LD: 15%
Con+LD+DUP: 16%
Con largest, but Lab+SNP+others maj: 20%
Con largest, but Lab+SNP maj: 6%
Lab largest, Lab+SNP maj: 8%
Lab+LD+DUP+SDLP+PC+Grn+Hermon: 6%
Lab+LD+DUP: 5%
Lab+LD: 5%
Lab+DUP: 1%
Lab majority: 0%
(Probabilities may not sum due to rounding)