What the report does

For each combined authority, take the winning party and vote share from its most recent mayoral election, then take every scheduled council election held across its member councils afterwards and aggregate them into a single ballot-box share. The gap between the two shows whether the mayor's mandate is holding, eroding, or has already been overtaken by another party.

How it's built

1. 1

   Fix the mayoral baseline

   Take the winning party and every party's share from the authority's latest mayoral election. Mayoral by-elections are excluded.

2. 2

   Find the councils that genuinely voted

   A member council counts for a year only if it held a full scheduled round, judged against the largest round it has held recently. Handfuls of by-elections don't qualify.

3. 3

   Aggregate the council vote

   Combine the ward results from those councils into a single party vote share for the authority in that year.

4. 4

   Measure the gap

   Set the mayor's party share at the ballot box against its mayoral share, and show which party now leads locally.

5. 5

   State the coverage

   Every figure carries how many member councils voted and what share of the whole mayoral area those councils represent.

How to read it (and how not to)

• • Mayoral and council contests are different votes. People split their ballot, and a strong personal mayoral vote routinely outruns the party's council vote.
• • Only councils that held a scheduled round are included, so most years cover part of the mayoral area rather than all of it. The coverage figure says how much.
• • Vote totals count every ballot cast in multi-member wards, so they measure party strength rather than a head count of voters.
• • Mayoral elections since 2024 use first-past-the-post; earlier contests used a supplementary vote, and only first preferences are compared.
• • This is a read on the state of opinion, not a prediction of the next mayoral result.