Psephology.AI

    By-election Vote Tracker

    Across 54 council by-elections in the last 90 days (to 2026-10-15), Reform UK averaged 27.7% (-0.9 pts), Labour averaged 23.2% (-7.5 pts), Conservative averaged 20.9% (-4.6 pts). Changes compare each ward with the last time it voted.

    Share in each by-election: Each party's best candidate's votes as a share of all parties' best-candidate votes in that ward.

    Change: Compared with the party's share at the previous scheduled election in the same ward. Only where the party stood both times.

    Roll up: Averaged over a rolling window (90 days by default). At least 15 contests are needed before a figure is shown.

    By-elections in last 90 days
    54
    Reform UK average share
    27.7%
    Labour average share
    23.2%
    Conservative average share
    20.9%
    Council by-elections, last 90 days to 2026-10-15
    PartyContestsAverage shareAverage changeGainsLosses
    Reform UK5027.7%-0.9 pts53
    Labour4923.2%-7.5 pts14
    Conservative5020.9%-4.6 pts24
    Liberal Democrats4117.1%+3.2 pts02
    Green3914.7%-5.9 pts22
    Independent168.0%-8.6 pts00
    All insights

    Insight 8

    By-election Vote Tracker

    How each party is doing in council by-elections, compared with the last time the same ward voted.

    Live, updated every Friday

    Every council by-election since the 1970s, each compared with the previous scheduled election in the same ward: share, change, gains and losses, rolled up into a running trend.

    A trend signal, not a poll. By-elections happen in a handful of places with low turnout. Change is measured against the election at which the departing councillor last won the seat, where we know it; otherwise against the latest scheduled election in the ward (labelled under each result). Where the ward's sitting councillors came from different parties and we don't know whose seat it was, we don't call it a hold or a gain.

    Where the parties stand

    Average share and change in recent council by-elections.

    Window

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    What the report does

    A rolling read of party fortunes from council by-elections, with every contest, gains and losses, and the long-run trend.

    How it's built

    1. 1

      Share in each by-election

      Each party's best candidate's votes as a share of all parties' best-candidate votes in that ward.

    2. 2

      Change

      Compared with the party's share at the previous scheduled election in the same ward. Only where the party stood both times.

    3. 3

      Roll up

      Averaged over a rolling window (90 days by default). At least 15 contests are needed before a figure is shown.

    How to read it (and how not to)

    • • A trend signal, not a poll.
    • • Parties that did not stand last time have no change figure and are counted separately.
    • • Scottish by-elections use STV, so they count for gains and losses but not for vote share.
    • • Northern Ireland is left out.

    What it reads

    • • Every council by-election result
    • • The previous scheduled election in the same ward (within 8 years)

    What you get back

    • • Latest headline shares and changes
    • • Every by-election with gains and losses
    • • Monthly long-run trend

    Readiness

    • Council by-election results

      Used directly.

    • Elections Centre by-elections 1983–2001

      Would fill gaps in older years.

    Live figures are held back until these are in place; no estimated numbers are shown in the meantime.