Looking at how the vote was distributed at the general election the Conservatives should, on a uniform swing, be able to secure a majority on a lead of about 6%. Labour would need a lead of almost thirteen points. On an equal amount of votes – 34.5% a piece – the Conservatives would have almost fifty seats more than Labour, Labour would need to have a lead of about four points over the Conservatives just to get the most seats in a hung Parliament. The way the cards have fallen, the system is now even more skewed against Labour than it was against the Conservatives.
How did this happen? It’s probably a mixture of three factors. One is the decline of the Liberal Democrats and tactical voting – one of the reasons the electoral system had worked against the Tories in recent decades was that Labour and Lib Dem voters had been prepared to vote tactically against the Tories, and the Lib Dems have held lots of seats in areas that would otherwise be Tory. Those factors have vanished. At the same time the new dominance of the SNP in an area that was a Labour heartland has tilted the system against Labour. Labour had a lead over the Conservatives of 9% in Scotland, but Labour and Conservative got the same number of Scottish seats because the SNP took them all.
Finally there is how the swing was distributed at this election. Overall there was virtually no swing at all between Labour and Conservative across Great Britain, but underneath this there were variances. In the Conservative held target seats that Labour needed to gain there was a swing towards the Conservatives (presumably because most of these seats were being contested by first time Conservative incumbents). In the seats that Labour already held there was a swing towards Labour – in short, Labour won votes in places where they were of no use to them, piling up useless votes in seats they already held
.And, of course, these are on current boundaries. Any boundary review is likely to follow the usual pattern of reducing the number in seats in northern cities where there is a relative decline in population and increasing the number of seats in the south where the population is growing… further shifting things in the Conservatives favour.