Green votes more than doubled. Their vote share more than tripled.
REPRODUCE THIS INVESTIGATION

Repeat the comparison from the council's candidate rows. No specialist software or individual voter data are needed.
You will need: A browser and a calculator, or Excel/another spreadsheet app for the candidate CSV

ACCESS AND DATA LIMITS
You can reproduce the counts and shares. You cannot reconstruct individual voter movements or motives from two aggregate election tables. Exclude rejected ballots from the valid-vote denominator and keep reported turnout separate.

WORKING FILES
Source notes: https://tallycat01.com/downloads/holborn-votes-and-vote-share-source-notes.txt
Timeline: https://tallycat01.com/downloads/holborn-votes-and-vote-share-timeline.csv

1. Open the correct 2024 table
Select Holborn and St Pancras in Camden's general election results. Copy all 12 candidate vote counts and locate David Robert Stansell's Green row.
Green votes = 4,030
Keep in mind: Do not use the separate Hampstead and Highgate table on the same page.
Open Camden's 2024 table: https://news.camden.gov.uk/general-election-results/

2. Open the 2026 by-election table
Copy all 15 candidate vote counts and locate Zack Polanski's Green row. Keep the 108 rejected ballots in their separate category.
Green votes = 8,928
Keep in mind: Rejected ballots do not contribute to the share of valid candidate votes.
Open Camden's 2026 table: https://www.camden.gov.uk/holborn-and-st-pancras-by-election-2026-results

3. Sum each year's candidate rows
In the downloaded CSV, filter election_date to one date at a time and sum votes. Do not add both elections together. The expected totals are shown below.
2024 total = 38,602
2026 total = 27,211
Keep in mind: These are totals derived from all candidate rows, not an electorate count.

4. Calculate the two shares
Divide each year's Green count by that same year's valid-vote total, then multiply by 100.
2024: 4,030 / 38,602 * 100 = 10.43987358%
2026: 8,928 / 27,211 * 100 = 32.81026056%
Keep in mind: Keep unrounded values for subsequent calculations.

5. Compare counts and shares separately
Divide the later count by the earlier count. Separately divide the later share by the earlier share. Subtract the percentage shares to calculate the percentage-point change.
Count multiple = 8,928 / 4,030 = 2.21538462
Share multiple = (8,928 / 27,211) / (4,030 / 38,602) = 3.14278332
Share gap = (8,928 / 27,211 - 4,030 / 38,602) * 100 = 22.37038697 percentage points
Keep in mind: A share multiple, a relative percentage change and a percentage-point change are different measurements.

6. Cross-check the scope
Compare the 2026 counts with Parliament and check its constituency history. This is one constituency with different candidates and election types, not a national survey or a record of individual switches.
Keep in mind: By the numbers explains the result without alleging deception.
Cross-check Parliament's result: https://members.parliament.uk/constituency/4105/election/560
Check constituency history: https://members.parliament.uk/constituency/4105/election-history

ADDITIONAL WORKING FILES
Candidate votes with sources · CSV: https://tallycat01.com/downloads/holborn-votes-and-vote-share-candidate-votes.csv
Calculation results · JSON: https://tallycat01.com/downloads/holborn-votes-and-vote-share-calculations.json
Recalculate in Python · ZIP: https://tallycat01.com/downloads/holborn-votes-and-vote-share-recalculate.zip

Evidence checked: 9 October 2026
Research and production assisted by AI