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Democratic Audit modelling of boundary changes

Democratic Audit modelling of boundary changes

Democratic Audit has modelled how constituency boundaries could change using the new rules contained in the Parliamentary Voting System and Constituencies Act 2011. The Act will see the number of constituencies reduced from 650 to 600 and, with a small number of exceptions, the electorate of each constituency will need to fall within 5 per cent of the UK average.

The model, devised by Lewis Baston, Senior Research Fellow, with assistance from Kevin Larkin, uses the December 2010 electorate figures, as the Boundary Commissions are required to do. It also adheres to a number of principles which the Boundary Commissions have indicated they will seek to apply, such as avoiding constituency configurations which cross English regional boundaries. In order to complete the local detail we have applied a number of additional assumptions, which are summarised in the presentation of the research.

It is crucial to underline that our model cannot be read as a prediction of what the Boundary Commissions will propose or, indeed, what the boundaries will look like once account has been taken of evidence presented at local hearings. However, the nature of the new rules which the Boundary Commissions will need to apply, combined with the intention to draw up boundaries within standard regions, does mean that much of the broad regional impact is already reasonably clear – particularly outside of the big cities. Moreover, given that support for the main two political parties has become increasingly geographically concentrated, the partisan impact within many individual regions is unlikely to vary substantially under proposals in which the local detail differs from our own.

Details of the research findings, and the approach used, have been published on the Guardian’s datablog

A summary of the methods and assumptions used, as well as summary details for each country and regional detail can be found here: 'The UK's new political map?'. Additional regional detail will be published during week commencing Monday 6 June.

The research also updates our previous estimates of the potential political impact of the 'reduce and equalise’ provisions had the new boundaries been in place at the 2010 General Election – published in August 2010 and January 2011. These previous studies used 2009 electorate figures and were based on the initial rules proposed in the draft Bill and are therefore superseded by these new estimates.  

Clearly, voting intentions have changed since 2010. It is certain that, were a General Election to take place tomorrow, the results would be quite different in some regions compared to the outcome in May 2010. However, we do not have sufficiently robust data on which to model the outcomes under current voting preferences – this would require a large-scale opinion poll; the May 2011 local election results are insufficient as a guide to how voting preferences may have changed across the UK as a whole.

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