The Area Maps and Tables each cover a specific geographical area, rather than a fixed set of constituencies (as is the case for the Constituency Charts and Election Results Tables).

• For a given geographical area, comprising a whole number of undivided 2024 parliamentary constituencies, the map is divide into unique sub-areas, each of which has a different history in terms of which constituencies it has been in since 1885.

• Each sub-area is denoted by a different number.  If a sub-area is split into non-contiguous parts then these are denoted on the map by letter suffixes, for example, as 2a, 2b etc., as necessary.  In drawing these sub-areas, boundary changes which do not affect any electors or at most just one complete street are not usually reflected on the map - the Area Map would use the most recent boundary in such cases.

• The table which accompanies each map shows the constituency history, with constituencies colour coded, so that the same colour does not apply to more than one constituency on each table, and the same colour is used when a constituency appears in more than one table.

• The far right hand column of of each table gives an estimate of the 2024 electorate in each sub-area, expressed as a percentage of the 2024 constituency size.  The sub-area size estimates have been derived using a methodology firstly based on the electoral changes between constituencies in 2024 as estimated either by the Media Guide or Electoral Calculus.  Then, the estimate of sub-Area size (as a percentage of its current constituency) within each area transferred in 2024, is calculated based on population, using a QGIS analysis of a constrained UK population file with a resolution of 100m.  The percentage estimates derived by this methodology are displayed to one decimal place.

By way of an example, in the Brent, Westminster & City of London Area Map and Table, the sub-area containing the Houses of Parliament, is named sub-area 40.  From the table it can be seen that this sub-area was in Westminster constituency from 1885 to 1918, in Westminster Abbey from 1918 to 1950, in Cities of London & Westminster from 1950 to 1974, in Cities of London & Westminster S from 1974 to 1997, and finally back in Cities of London and Westminster from 1997 onwards  It is estimated that sub-area 40 contains 14.0% of the electorate in the 2024 constituency Cities of London & Westminster.

Minor changes resulting from interim reviews carried out by the Boundary Commissions between the main periodical reviews are generally not shown.  A few exceptions are made where such changes are more substantial (e.g. Milton Keynes 1992, Oxford 1964).  Sometimes the boundaries shown are those revised by an interim review, especially if these were in force for more elections than the original.