UK Parliamentary Constituencies

This website provides information on the changing composition of parliamentary constituencies in the United Kingdom since 1885.  Have you ever wanted to know at a glance:

• How constituencies created at each boundary review have been related to their predecessors?

• The changing picture of General Election results in each part of the country?

• For any precise location, which constituencies it has been in over time?

Every constituency that has existed since 1885 has been allocated to one of 116 groups.  Starting with the first group, covering the London Borough of Westminster and the City of London, a new group was added to the site every week from May 2021 until June 2023.  

Now that the four United Kingdom Boundary Commissions have submitted their final proposals to Parliament (at the end of June 2023), the process of incorporating the new constituencies has begun.  The new constituencies came into effect at the 2024 General Election.  A new group is being added under the 'New constituency groups' tab above at approximately weekly intervals and should be complete at about the end of 2024.  In creating these updated analyses, the methodology and presentation has been changed in some cases.     

For each group there are separate charts, maps and tables:

(a) Constituency Charts.  These charts show how the constituencies have evolved over time with transfers of electors between them.  The size of transfer is indicated by the format of the line between constituencies, and very small transfers are omitted.  Only years in which there are changes affecting these constituencies are shown as layers in the chart.  Transfers that are to or from another area these are shown to or from dashed boxes.

(b) Election Results Tables.  These tables show the outcome of every general election since 1885 for the constituencies shown in the chart above, colour-coded according to the main party groupings.

(c) Area Maps and Tables.  There may be more than one map per area to provide clarity.  Each map divides the area covered into distinct sub-areas each of which has had a different sequence of constituencies in which it has been since 1885.  There is a table for each map which acts as a key.  The tables also show an estimate of the relative size of the electorate in each sub-area denoted on the map.

Constituency maps 

Maps for the whole of Great Britain and Northern Ireland are now available here.  There is also the ability to download the underlying data, so that it can be used in other projects.

More detailed information on the presentation and methodology can be found in the information section.  Note that historic constituencies shown in a Constituency Chart may have covered a geographical area that is shown on more than one Area Map.

This website is continuously being updated. For a list of the latest changes please see the changelog.