How much disruption do we want to the UK’s electoral map? We want constituencies to be equal in size – but how equal? And do we want fewer MPs? An article in The Independent on 11 July 2015 suggested that some Conservative MPs are already concerned about the impact on their constituencies if the number of MPs is reduced but unless these questions are addressed quickly another very disruptive exercise in redrawing constituency boundaries will start early next year. In part one of this two-part blog, Ron Johnston, David Rossiter and Charles Pattie consider the review that was aborted in 2012 and outline the challenges currently lie ahead for the 2016 review.

The Conservative manifesto for the 2015 general election included a statement that:

‘We will also continue to reform our political system: make votes of more equal value through long overdue boundary reforms, reducing the number of MPs…’

This was not a commitment to do something new; legislation is already in place to achieve those goals and the manifesto commitment was thus simply one to ensure that they were achieved. But what do the Conservatives want to achieve, and what will it mean for the next election?

The Parliamentary Voting System and Constituencies Act, 2011 introduced a number of fundamental changes to the way in which Parliamentary constituency boundaries are defined. Under the previous legislation they were reviewed every 8-12 years; each of the four nations of the UK had a guaranteed minimum number of MPs – which meant that some parts, notably Wales, were significantly over-represented relative to others (at the 2015 election, the average Welsh constituency had 57,057 registered electors whereas the English average was 72,853, the Northern Irish 68,705 and the Scottish 69,403); and the Boundary Commissions were only required to try and make constituency electorates as equal as practicable when they had taken account of local government boundaries and communities of interest and, as far as possible, kept change to a minimum.

The result was great variation in constituency sizes. In 2015, although half of all constituencies had electorates between 66,000 and 75,000 (around a median of 71,000), one-tenth of all MPs represented less than 62,000 registered electors and another one-tenth represented more than 79,000. The Conservatives deemed this unfair – and also believed (rightly) that the variations favoured the Labour party. Furthermore, over time between reviews the discrepancies had increased – again, to Labour’s benefit as electorates in its constituencies tended to grow more slowly (or even decline) relative to what happened in Conservative-held seats.

The 2011 Act introduced five major changes:

1. The number of MPs was to be fixed at 600 – a reduction from the current 650;
2. There was to be a single average electorate (quota) applying to the entire UK;
3. All constituencies, with four exceptions (two in Scotland and two for the Isle of Wight), were to have electorates within +/-5% of the quota;
4. Other factors, such as community of interest, local government boundaries and minimising change could only be taken into account within that strict tolerance; and
5. A review was to be held every five years, consistent with the timetable for fixed five-year Parliaments.

The Boundary Commissions produced recommended new constituencies within these rules within a year of starting the exercise in March 2011, held public consultations, and published revised recommendations by the end of 2012. But then the Liberal Democrats (responding to the coalition government’s failure to enable House of Lords reform) voted with Labour to halt the procedure.

The Act was not amended by that vote other than by delaying its implementation. A new review now has to be undertaken, under the same rules, starting in March 2016 – using electoral data from the electoral register compiled in autumn 2015 – and reporting to Parliament by October 2018. A new set of 600 constituencies will then be in place in time for the 2020 general election.

The main feature of the aborted review was the amount of disruption it introduced to the UK’s electoral map. Very many of the existing constituencies were very substantially changed as a result of the number of seats having been reduced, the introduction of the single quota, and the +/-5% tolerance, and many MPs faced the prospect of seeking re-election from a constituency very different from the one they currently represented – if they could find one at all. Furthermore, many of those new seats did not fit as easily into the local government boundaries as had their predecessors; many communities were split between constituencies; and areas with little in common were combined together in constituencies whose parts did not form a coherent whole. Until the 2011 Act, MPs had represented places; after its implementation they would represent numbers.

The reason for this disruption is readily illustrated by the situation in Wales during that review. It currently has 40 MPs, who represented electorates ranging from 41,198 to 73,705 at the 2010 election, with 28 of them having fewer than 60,000 registered voters. With the new UK quota of 76,641, Wales was entitled to only 30 MPs, and the +/-5% tolerance meant that all 30 constituencies had to have electorates between 72,809 and 80,473. Only two of the existing constituencies did, so in effect the entire constituency map of Wales had to be redrawn to fit into the new rules.

When the Boundary Commissions start work again in 2016, at least a similar amount of disruption can be expected, and MPs – including the large number of new members (especially those representing the Conservatives and the SNP) – face the same problems as were encountered in 2012. There may be some slight changes in how the Boundary Commissions act – the English Commission has indicated a readiness to split wards in certain circumstances in order to create ‘more viable’ constituencies (something it was not prepared to do in 2011-2012) but the fundamentals have not changed.

Nor, despite what some have hinted, can the Commissions start with the set of 600 constituencies they had ready in 2013, because the numbers have changed. The electoral data on which the allocation of seats to the four countries will be made have yet to be assembled, and with the recent introduction of Individual Electoral Registration there is much uncertainty as to how many will be on the roll this autumn; research two years ago suggested that only 85% of those eligible were registered, and many believe that the figure will be less than that at the end of this year.The table shows how variations in the number of registered electors over a short period can influence the distribution of seats across the four countries. The second column shows the number of MPs for each in the aborted review that started in 2011 using electoral data for 2010. (Only 596 of the 600 seats are allocated because the four ‘protected constituencies’ – two in Scotland and two in the Isle of Wight – are excluded from the calculations.) The next column indicates the allocations if the electoral data for the end of 2014 were used: Scotland would gain three seats from its 2010 allocation – presumably because of the extra enrolment for the Scottish independence referendum – whereas England would lose two and the Welsh contingent of MPs would fall to 29. After the electoral roll was compiled in late 2014, however, people could register to vote at the 2015 general election until 10 April of that year, and over one million did. Using the electorate figures for that election, the final column shows a small change from the 2010 data – one extra seat for Scotland and one less for England.

Such a change might seem small, but we calculated that if England were to lose a seat, and the reduction was in the Southwest region, then all of the constituencies in Cornwall, Devon and Somerset would have to be redrawn in order to fit the rules. A small difference in the allocation of seats can result in substantial changes locally – and it is very likely that will occur.

And, of course, changes in the population distribution will mean that some of the constituencies devised by the Boundary Commissions in 2011-2012 are now too large – relative to whatever the new quota and its +/-5% tolerance are – and others are too small. Modifications will be needed.

That’s not all. Wherever possible, the Boundary Commissions use wards as the building blocks in recommending constituencies, in an attempt to create seats that combine local communities – although the English Commission was more committed to that guideline than the others. In England, the continuing work of the Local Government Boundary Commission means that much of that map on which the Parliamentary Boundary Commission relies has been changed. Since 2010 new ward arrangements (some partial, many complete) have been put in place in over 100 local authorities, and these will form the basis on which work on the new maps commences next year.

Check back tomorrow for the second part of this blog, which makes the case for amending the Bill in line with Political and Constitutional Reform Committee recommendations made in March.

About the Authors

Ron Johnston is a professor in the School of Geographical Sciences at the University of Bristol; David Rossiter is a retired Research Fellow who formerly worked at the Universities of Bristol, Leeds, Oxford and Sheffield; and Charles Pattie is a professor in the Department of Geography at the University of Sheffield. They have written together on the Boundary Commissions and constituency definition in the UK since the early 1980s and co-authored The Boundary Commissions: Redrawing the UK’s Map of Parliamentary Constituencies (University of Manchester Press, 1999).