We know the Liberal Democrats didn’t end up increasing the number of seats they hold, but they did substantially increase the number of second places they have, and have more winnable marginals. The notional 2005 figures had the Lib Dems holding 62 seats and in second place in 188. Following the 2010 election the Lib Dems hold 57 seats, but are in second place in 242. On the 2005 notional figures the Lib Dems were within 10% of the winning party in 31 seats, now they are within 10% in 45 seats.
Conversely, Labour held 348 seats and were in second place in 151 – a total of 499. Those figures are now 258 and 160 (assuming they retain second place in Thirsk and Malton), a total of 418 and suggesting they have dropped to third place in an additional 81 seats.
Based on the 2010 results, the Conservatives would need a swing of 2% in order to gain an overall majority (meaning they would still need a lead of roughly 11 points over Labour to win an overall majority). In short, any effect from unwinding tactical voting or shifting voting patterns has not made the system kinder to the Conservatives.
However, it has got less kind to Labour. On the notional 2005 result, Labour could have got an overall majority by getting an equal number of votes to the Conservatives. From the 2010 results, Labour would require a swing of 5% in order to gain an overall majority, the equivalent of being 3 psoints ahead of the Conservatives. For Labour to become the largest party in a hung Parliament they would need a swing of 1.7%.
We have past instances of Scotland behaving somewhat differently to the rest of Great Britain (most obviously 1992, when England and Wales swung towards Labour, but Scotland swung to the Tories). This election produced an extreme contrast – in England and Wales there was a swing of between 5-6% from Labour to the Conservatives, in Scotland there was a 1% swing towards Labour, mostly at the expense of the Liberal Democrats, whose vote rose in England and Wales.
More unusually there was a significant difference between London and the rest of England. In London the swing to the Conservatives was only 2.5%, compared to 6.1% in the rest of England. Labour’s vote fell by 2.3% in London, but 8.2% elsewhere in England. Perhaps some of it is a Boris effect, but some will also be the high ethnic minority population in London. Labour’s vote seemed to hold up better in seats with a high ethnic minority population, and in some seats with a high proportion of Muslim voters Labour’s vote share increased as the Iraq effect from 2001 faded.
Marginal swing, and a puzzling question
The Conservatives performed only slightly better in marginal seats. In the country as a whole they had a swing of 5.03% from Lab=>Con, in Lab held marginal seats with a majority of under 10% they got a swing of 6%, in Labour held marginal seats with a majority between 10% and 20% they got a swing of 5.13%. This does raise the question of why they got so many seats – they managed 305 seats, when on a uniform swing of 5% they should have got only 289. If they didn’t do better in the marginals, how come they won more seats than they should have?
There are two reasons. Firstly, while the mean average swing in Conservative marginals where they needed a swing of between 5% and 10% was only 5.13%, the median swing in those seats was 5.84%. The mean was dragged down by some Scottish and London marginals where the Tories went backwards, but in most seats in that range the Conservatives did slightly better than their average performance across the country. The other reason is sheer, dumb luck. There were 11 seats where the Conservatives and Labour were within 1% of each other and the majorities were under 500 votes, the Conservatives won 8 of them.