Newsnight ran a good piece yesterday explaining some of the problems with forecasting the next general election, including a very interesting contribution from Chris Hanretty from the UEA.

One of the best features of Chris’s model is that it produces precise probabilities for each party to win each seat, which we can compare to Ladbrokes’ constituency odds. I haven’t been through every seat, although I have had a good look at the Scottish ones already, because his forecasts produce some startling results there. If you like his approach, then there are some fantastic bets to be had, all on the SNP. Here are just a few seats I picked out with the Ladbrokes’ SNP odds and those suggested by the model.

ConstituencyLadbrokesHanretty
Gordon4/71/100
Falkirk5/61/50
Argyll and ButeEvens1/10
Caithness, Sutherland and Easter Ross2/11/16
Fife North East9/42/5
Glasgow East5/24/11
Ross, Skye and Lochaber3/11/4
Glasgow Central4/18/13
Paisley and Renfrewshire South5/12/1
Orkney and Shetland10/111/8

Before piling in to the prices, it’s worth having a good look at the FAQs on Chris’s site. They are completely open that the local performance of the Liberal Democrats is a major source of uncertainty, and I think that has caused a lot of the differences above. For example, in 2010 the SNP finished 51% behind the Lib Dems in Orkney & Shetland. I don’t think many people would be in a hurry to take 11/8 about them turning that around. As they point out on the site: “We are not gambling on the basis of these predictions”.

With it now being odds-on that we have a hung parliament next year, some are now speculating on the chances of another election having to be called pretty swiftly.

It last happened after the indecisive result of the February 1974 election, the only time since 1910 that there have been two in the same calendar year. So, it’s not very common in UK politics, but the chances of a very messy outcome in next May are increasing by the day. If we take the mid-point of Ladbrokes’ current seat totals betting, the parliament that would emerge would look something like this:

There would really only be one stable option here to get to a majority of 326; a Lab/Lib coalition (currently a 5/1 shot with Ladbrokes).

But, let’s imagine a scenario where UKIP and the SNP do a bit better than our betting currently suggests, which many people think they will, and the Tories get a lot closer to Labour:

What happens now? Con+LD+UKIP gets to 325, but that doesn’t seem all that plausible or stable an arrangement. Lab+LD+SNP gives 329 seats, although if the SNP continue to abstain on English only issues at Westminster, that might not work either for a lot of legislation. Maybe some Northern Irish MPs and Plaid Cymru can be persuaded to prop up such a government, but it wouldn’t be a smooth ride. Anything close to this sort of result could easily lead to a fresh election, although Steve Richards thinks that the Fixed Term Parliament Act makes it unlikely, however complicated the maths is.

Until recently, most of us had been assuming that the Greens would have enough of a job holding on to their one seat in Brighton Pavilion. Perhaps an outside chance in Norwich South, but that was about it. Some good recent national opinion polls have led to speculation that they might do a bit better than that.

Let’s have a look at their chances in the 12 target seats mentioned in The Guardian, as indicated by the current constituency odds at Ladbrokes:

SeatWin 2010%Maj 2010Green Odds
Brighton PavilionGreen2.410/11
Norwich SouthLib-Dem0.76/1
Bristol WestLib-Dem20.510/1
St IvesLib-Dem3.725/1
Sheffield CentralLabour0.425/1
Holborn & St PancrasLabour18.225/1
Liverpool RiversideLabour36.525/1
SolihullLib-Dem0.333/1
York CentralLabour13.933/1
Oxford EastLabour8.933/1
Reading EastConservative15.233/1
CambridgeLib-Dem13.650/1

Bristol West came as a bit of a surprise to me when people started backing it at 100/1. Now 10/1, that would be a very expensive result for Ladbrokes. Perhaps not quite as bad as Brighton Pavilion in 2010, which was one of the biggest betting contests out of all 650 UK constituencies. Caroline Lucas only just scraped home back then, but the Greens had been backed in from 5/1.

Norwich South was their number two target at the last election, and there’s not reason why they couldn’t go close again in 2015. If, as expected, the Liberal Democrats are turfed out with a vastly reduced vote, the seat is very much up for grabs between Labour and the Greens. I’m starting to think 6/1 might be a big price there.

It looks like their other hopes are mostly seats with big student/university populations and classic Guardianista territory. It looks a big ask for them to actually win any of these, so we’re quoting 25/1 that the party wins six or more seats next May.

Sky News have reported on some “internal UKIP polling”, which the say reveals UKIP’s top dozen target seats. Ladbrokes have odds on every seat in Britain and, based on those, we can allocate a probability of UKIP winning each of these twelve seats.

SeatWin 2010Maj%UKIP OddsUKIP Win %
Thanet SouthConservative16.611/1043.09%
Great YarmouthConservative9.915/832.01%
ThurrockConservative0.22/130.34%
Boston & SkegnessConservative28.85/225.76%
Thanet NorthConservative31.24/117.63%
Great GrimsbyLabour2.24/118.01%
Portsmouth SouthLib-Dem12.64/118.00%
EastleighLib-Dem7.25/115.03%
Sittingbourne & SheppeyConservative25.58/19.91%
Forest of DeanConservative22.712/17.02%
Worthing East & ShorehamConservative22.912/17.08%
AylesburyConservative23.716/15.45%

The top three in the list are especially promising as there is every chance they could be three-way contests and something around 35% of the vote could win any of those.

If UKIP high command had just looked at Ladbrokes’ odds, then the bottom four on the list wouldn’t have made the cut. All look like ultra safe Tory seats and it will take a huge effort to win any of these. Aylesbury has a majority of over twelve thousand, but I guess the party are hoping to exploit the HS2 issue here.

Party workers in Castle Point, Folkestone and Rotherham will be a bit disappointed not to have been included, as the betting would suggest that they are all much better prospects than the likes of Forest of Dean.

We’ve got some betting on how many seats UKIP will win in total next year; it’s 5/1 that they manage ten or above.

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