Quite simply the red team’s vote is distributed more efficiently
There’s a widespread assumption amongst many Tories that the new boundaries are a universal palliative which solve all the apparent bias to Labour within the system. This is wrong.
The biggest reason why Labour can secure a majority with a much smaller vote share than the Tories is that the party’s support in general elections is distributed more efficiently.
No boundary review can deal with that.
Just look at the chart based on data from Denis Kavanagh’s and Philip Cowley’s The British General Election of 2010. The shows the mean vote changes in 2010 of the main parties in different categories of seats based on which came first and second in 2005.
Compare the big differences in the Labour vote changes in each category with the relatively consistent change in the Tory vote share.
As can be seen the biggest drop-off in Labour support was in those seats which had no impact on the overall outcome – those where the Tories were in first place over Labour in 2005.
In seats where the yellows were fighting Labour there was no sign of any anti-Labour tactical voting from Tory supporters.
In LD/LAB seats both the Tories and Labour did better than average whereas in LAB/LD seats the vote share for Clegg’s party rose by only 0.4 percent – half the national average.
In CON-LD battle-grounds there wasn’t much evidence of any new tactical voting by Labour supporters to stop the blues making progress.