Politics: The Liberal Democrats hold the key to boundary reform – and therefore the next election

The Cameroons believe they have come up with a policy that will deliver at least 20 more Tory seats at the next election. No. 10 is, understandably, determined to get this measure through: nothing else promises them anything like the same electoral dividend. But this silver bullet isn’t a tax cut or a new approach to Europe. It is a set of changes to the constituency boundaries.

This boundary review has been designed to limit the pro-Labour bias in the Westminster electoral system. It reduces the number of parliamentary seats from 650 to 600, which notionally reduces the number of Labour MPs by 28.

If its recommendations are enacted, the effect on British politics would be dramatic. The pollster Anthony Wells calculates that if an election were held today on the current boundaries, Labour would be two seats short of an overall majority. When you consider that there are five Sinn Fein members who don’t take their seats, that translates into a majority of sitting MPs.