Director of Political and Social Research

This week the independent Boundary Commission for England has reported its provisional recommendations for changes to the Parliamentary boundaries ‒ the constituencies for which MPs are elected.

Boundary reviews are a vital part of our electoral system ‒ if everyone is to have a roughly equal say in which party governs the country, each MP needs to represent roughly the same number of voters. As the population in different parts of the UK changes over time, the electorate of MPs seats also changes ‒ with the electorate in some seats dropping and in others growing. Boundary reviews iron out these differences and put things back on a level footing.

They are, however, rarely uncontroversial as they have a direct relationship on how well the political parties do. Because the population in Northern inner-city seats (normally Labour) tends to fall relative to Southern suburban seats (normally Conservative), boundary reviews normally end up helping the Conservative party. This boundary review is particularly controversial because it also involves cutting the number of MPs by 50 and a tightening up of the rules the Boundary Commission have to follow when proposing seats, meaning all seats must now have an electorate within 5% of the average, even if this means crossing county boundaries.

On the existing boundaries the Conservative party need to be around 11% ahead in the overall vote to win an overall majority, while Labour could achieve an overall majority with a lead of 3%. The Conservative party hopes that making seats more equal will remove some of this perceived bias in the electoral system. Labour has accused the government of seeking to gerrymander the boundaries to their advantage.

Our first projections based on the proposed boundaries suggest that they will help the Conservatives somewhat. If the votes from the 2010 general election had been counted on the new boundaries, the Conservatives would have won 5 fewer seats, the Liberal Democrats would have won 7 fewer seats and the Labour party would have won 18 fewer seats. While the Boundary Commissioners for Wales and Scotland have yet to report, it looks likely that the Conservatives would have been very close to an overall majority if the last election had been fought on the new boundaries in a House of Commons of 600 MPs.

However, if Conservatives hope the new boundaries will entirely remove Labour's current advantage in the electoral system they are likely to be disappointed. Only part of the current disparity is down to the different seat sizes, it is also due to lower turnout in Labour seats, and people voting tactically against the Conservatives.

As well as the effect upon the wider political picture, boundary changes also have a big impact on individual MPs, who may see their seats abolished or changed. On the provisional boundaries, high-profile MPs who may suffer under the new boundaries include Ken Clarke (his Rushcliffe seat is abolished), Iain Duncan Smith (his safe Conservative Chingford & Woodford Green seat is divided between two marginals - Chingford & Edmonton and Wanstead & Woodford), Alan Johnson (his Hull West & Hessle seat becomes an ultra-marginal) and Hilary Benn (his Leeds Central seat is abolished).

So far these recommendations are only provisional ‒ there now follows a twelve week consultation period and public hearings, after which the Boundary Commission will review their recommendations. When the final recommendations are completed by 2013 the new boundaries then face a vote in Parliament before they are implemented.

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