By Chris Prosser and Stephen Fisher.
Every May local election results are analysed as indicators of the state of the political parties and scrutinised for what they tell might tell us about the outcome of the next general election. That general election is tomorrow. Although a lot has happened in politics since May 2019, and especially since May 2018, it might be worthwhile reminding ourselves of what happened in the local elections then and what those results portend for the outcome this week.
In 2015, when the polls failed to anticipate a Conservative majority, one of the more successful forecasting models was Chris Prosser’s one based on the 2013 and 2014 rounds of local elections. Unlike the polls – which showed the Conservatives and Labour neck and neck – that model forecast a four point Conservative lead in vote share. Using a uniform change projection, the forecast shares predicted a Conservative tally of 296 seats for 2015, short of an overall majority but better than a uniform projection from the final opinion polls and the best of a set of twelve academic forecasting models for that election.
Applying the same method again, the table below shows that both the 2018 and 2019 rounds of local elections point to a clear lead for the Conservatives in a subsequent general election. However, the forecast shares of the vote from both rounds do not suggest a big enough lead for the Conservatives to be sure of an overall majority. On the average of the two set of vote shares, coupled with a uniform change projection (also using last night’s YouGov MrP projected SNP and PC vote shares) points to a very narrow Conservative majority of 8.
| Party | Forecast share based on 2018 results | Forecast share based on 2019 results | Average forecast share | Standard Error of share forecast | Seats forecast |
| Con | 40.8 | 36 | 38.4 | 4 | 329 |
| Lab | 33.8 | 29 | 31.4 | 4 | 231 |
| LD | 13.4 | 15.4 | 14.4 | 4 | 23 |
| Other | 12 | 19.6 | 15.8 | 4 | 65 |
The fact that a forecast based on local elections 7 and 19 months ago should be so close to last night’s YouGov MrP projection of Con 339, Lab 231, LD 15 is remarkable. There is just a difference of 10 seats for the Tories and none for Labour.
Given that since the 2018 local elections we’ve had May’s Deal and the first missed Brexit deadline, and since the 2019 local elections we’ve seen Brexit Party and Lib Dem success in the European parliament elections, a new prime minister, a new Brexit withdrawal agreement, and another missed Brexit deadline, it is even more surprising that most opinion polls now do not differ profoundly from what previous local elections suggested would happen.
Elections Etc 
I do think this is a very promising Indicator. The spread in the Opinion Polls seems so wide as if two different weighting factors are in use.
https://notthegrubstreetjournal.com/2019/12/11/capons-turkeys-and-norweigan-blues-ge2019will-santa-finds-out-whose-naughty-and-nice-who-will-win-the-race-for-number-ten-grub-street-says-corbyn-wiki-ballot-says-johnson-who-believes-in-santa-a/
Hers my own bale string analysis with a bit of gaffer tape, every little helps it may not be pretty but its enthusiastic and well meant.
I suspect you chaps are on the money.
The range of seats predicted by the polling extremes is 14 seat majority at the low end and 114 seats at the high end, the final vote, in my opinion, will break one way or the other on the day, depending on two things, Turnout as in 2017 will be key, is it the Brexit election and will disgruntled Brexit voters from 2016 turn out in force and Vote for “BRINO”, and secondly The don’t know’s, will they go for one side or the other or simply not bother?
So my prediction is this, it will either be a Hung Parliament with Labour short by up to 30 or so seats or a Tory Majority in excess of 100 seats. And the telling factor will be whether or not the Norweigan Blue is in fact deceased.