A previous forecast for the Scottish Local Elections was made before the General Election announcement on April 18th. Upon reviewing the forecast, I found that I had not allowed in the forecast of changes in numbers of council seats, for the impact of different average population per council seat. Allowing for this factor roughly offsets the movement in opinion since that announcement. In particular the fact that a Labour Councillor represents on average a large population than a councillor from other parties offsets the impact of a small increase in support for Labour since the General Election announcement. I see no reason to revise significantly my previous forecast of Labour to lose 250 seats, with the Conservatives to gain 150 and the SNP 100.

After the General Election was announced at least two Scottish opinion polls of Westminster voting intentions have been produced – one by Panelbase for The Sunday Times, the other by Survation for the Sunday Post. Both polls show the SNP down and both the Conservatives and Labour up slightly. One problem with using this opinion data is that people might vote differently in the local elections. For instance, in Scotland as a whole, Independent candidates in 2012 received 12% of the First-Preference votes and won 16% of the seats. I would expect that that the SNP would lose out the most to Independents, followed by maybe the Conservatives and the Liberal Democrats. This hypothesis can be validated against the data. The University of Strathclyde’s “WhatScotlandThinks.org” has the opinion poll data going back to 2007. For 2007 and 2012 I compare to percentage shares of seats votes with the opinion polls nearest to the local elections in Figure 1.

There is a result that I did expect. That is the Conservatives did comparatively worse in terms of seat percentage to opinion poll percentage. This was worse in 2012 than in 2007, as their share of First Preference votes fell in many wards below the threshold required to win seats. What I did not expect was that the SNP’s seat share was about the same as the opinion poll percentage in 2007 and slightly above that level in 2012, despite Independents winning 16% of the seats. Most unexpected is the Labour Party, which has the biggest deficit between opinion polls and seat share. There are three vague factors, that might be valid. That is different voting behaviour in local elections and general elections; lower voter turnout in Labour-voting wards and inaccuracies in the opinion polls. In the first it could be that some people were voting SNP in the local elections and voting Labour in General Elections. But this does not gel with what happened in the 2011 Scottish Assembly elections and the 2015 General Election. There is another factor. Local Councils represent different populations, which only partly reflected in the size of the council chamber. The most populous is Glasgow, with an estimated mid-2015 population of 606,300 and 79 Council seats.  The least populous is Orkney Islands, with an estimated mid-2015 population of 21,500 and 21 Council seats. So a Councillor in Glasgow will represent nearly nine times the number of people as in Orkney. There are good reasons for this differential. If the Councillors per head of population were made roughly equal (4390), then Glasgow council chamber would increase to 138, and Orkney would reduce to 5. But this does impact overall. Using the 2012 seats and within each council, dividing the population by the seats, gives figure 2.

About half of  the difference between the Labour Party’s differential between First-Preference vote share and seat share can be explained by the fact that their support is concentrated in the larger council areas where the average seat population is larger. The SNP were also impacted by larger than average seat population , but not by nearly as much.

This does not matter for seats won on councils, but it does impact on the net change in council seats. In particular, like others, I believe that the SNP will make large gains from Labour in the cities and larger towns, with Glasgow being the key area. But I also believe that the SNP will lose council seats to the Conservatives and the Independents. For this reason, I estimate that the average SNP seat population will increase by about 5%. With it they should gain control of 5 to 10 councils. However, if the drop in General Election support is from around 47% to 41% the net seat gain could be around 50, instead of the 100 previously predicted.

Labour are hit with three combined impacts of the likely fall in the first prefence votes. First is the failure to reach the threshold first preference votes to win seats. Second is that this threshold will be a higher percentage of the vote than for the Conservatives or the Liberal Democrats, as Labour have fielded more than one candidate in nearly 150 wards.  With such a low share of the vote, under the STV system Labour Party candidates will be competing against each other for votes. Third is that Labour have larger than average population per seat, so the percentage of the seats won will be lower than the opinion polls suggest. For these three reasons combined, even if the General Election show a slight recovery from 15% to 18% of the popular vote, their share of the Scottish council seats won, could be still be less than 13% of the total, the point where total number of seat losses exceeds 250.

Kevin Marshall