The Constitution Unit


Constituency Boundary Reviews

A project examining government proposals to change the system of reviewing Westminster constituencies, focusing on safeguarding the review process from any danger of undue political interference.

Boundary review

Read our initial analysis

Read our written evidence to the
House of Commons Public Bill Committee

Read our oral evidence to the
House of Commons Public Bill Committee

This research project examined proposals introduced by the government in May 2020 to change the system of reviewing Westminster constituencies. The boundaries of parliamentary constituencies in the UK are reviewed periodically by independent Boundary Commissions to ensure that constituencies are broadly equal in numbers of eligible voters while also respecting local ties. Until 2020, parliament could block the Boundary Commissions' proposals. Under the new procedures  which became law as the Parliamentary Constituencies Act in December 2020  that power was removed.

Our research, led by Alan Renwick and Robert Hazell, concluded that this change was welcome, as it strengthened the principle of independence of the boundary review process from political interference. It noted that no comparable veto rights existed in comparable democracies such as Canada, Australia, and New Zealand, and that these systems worked well.

But our research also found that stronger safeguards were needed to protect the Boundary Commissions from interference by government. While there was no evidence that such interference had occurred, the removal of the parliamentary veto could increase incentives for it. Stronger safeguards already exist for many other bodies, notably the Local Government Boundary Commission for England. In particular, the research found that implementing non-renewable terms for Boundary Commissioners would mean they would be less susceptible to pressure, and setting down rules for their appointment in law would make for a more transparent process. This proposal was backed by the House of Lords, but subsequently rejected in the House of Commons.

This work built on Robert Hazell’s review for the government of the Local Government Commission in 1998, which recommended a merger with the Parliamentary Boundary Commission. The Unit has also carried out wider work on constitutional watchdogs.

This analysis was cited by the House of Lords Constitution Committee and in the committee stage debate in the House of Lords.