Parliamentary Boundary Reviews: What Next? Contents


There are currently 650 parliamentary constituencies in the UK, each one represented by a Member of the House of Commons. Constituency boundaries shape our elections. They influence a candidate’s chances of winning an individual constituency, and determine how a party’s national vote translates into seats in the House of Commons and therefore who can form a Government.

Constituency boundaries are periodically reviewed by independent Boundary Commissions, one covering each of the constituent nations of the UK, using rules laid down in legislation. These rules were changed in 2011 by the then Coalition Government. The new legislation fixed the number of seats in the House of Commons at 600. The electoral quota, the average number of electors in each constituency, which had previously been different for each of the four nations of the UK was also made the same across the country and all seats had to be within 5% of it.

The changes to the rules and the reduction in the number of MPs have made the implementation of new boundaries contentious. The previous review, which was due to report in 2013, was cancelled.

The Commissions must publish their latest recommendations in September this year. Parliament will then have to decide whether or not to implement them.

Until a new set of boundaries is implemented, the existing ones continue to be used. These were introduced in 2005 in Scotland and 2010 in the rest of the UK, and were mostly based on data from 2000 and 2001. If the House of Commons chooses not to implement the Commissions’ recommendations, there are two options for the General Election in 2022: i) to use the existing unequal boundaries, based on data that will, by then, be over twenty years old, or: ii) to amend the law and require a new review.

A new review would, realistically, require the truncation of the boundary review process so that new boundaries could be implemented by May 2022. This would have both costs and risks. In particular, it would reduce the extent of the Boundary Commissions’ consultations with local communities on their proposed boundaries. However, this is an option worth exploring given the likely alternative.

Should the Government decide to wait until the autumn (when the Boundary Commissions publish their final recommendations) to consult Parliament it is unlikely that there would then be sufficient time to pass the required legislation and deliver a satisfactory review. We therefore recommend that the Government should give the House of Commons an early opportunity to debate the options for reform and consider the risks of legislating to end the current boundary review, in order to establish whether a consensus can be reached in time for legislation to be passed before the summer recess.

16 February 2018