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Redrawing the Parliamentary map

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Press release issued: 4 July 2014

A report on the UK rules for Parliamentary constituency distributions by Professor Ron Johnston of Bristol's School of Geographical Sciences, and colleagues David Rossiter and Charles Pattie, was launched at the Houses of Parliament this week.

The launch was sponsored by senior members of all three main political parties and was attended by some 20 MPs, who gave it a very positive welcome.

A review of Parliamentary constituencies, which would have resulted in most of the 600 seats contested at the 2015 general election being very different from the current 650, was halted before its completion in 2013.  The potential disruption alarmed many MPs and party organisations.

In 2016, the Boundary Commissions are required to begin the task of producing a new set of constituencies for the 2020 general election but the very disruptive consequences of the previous exercise have generated questions regarding the nature of the new procedure.

In their recently published research, Professor Johnston and colleagues assess whether changing the rules for defining constituencies could reduce the disruption to the map of constituencies.

Currently, in order to ensure every vote has equal value, the number of voters for each seat has to be within +/-5 per cent of a UK-wide norm for constituency electorates (in 2011, this 'electoral quota' was 76,641 for a 600-member and 70,708 for a 650-member House).  Professor Johnston found that increasing this +/-5 per cent tolerance would reduce the disruption to constituencies somewhat while maintaining the general principle of electoral equality.

However, at least one-third of all constituencies would almost certainly have to experience major change, regardless of whether the number of MPs was retained at the current 650 or reduced to 600.

The full report Equality, Community and Continuity: Reviewing the UK Rules for Constituency Distributions is available from the McDougall Trust

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