U.K. by-election race desk · Holborn and St Pancras
Labour has to defend Starmer’s seat without Starmer.
Keir Starmer resigned from the Commons on 1 September 2026, ten weeks after leaving Downing Street. The writ has not been moved, no date is set, and nobody has declared. This page is what a forecast honestly looks like at that stage.
Where the race stands
Why there is no single number here
Vote-Scope does not publish a point estimate for a by-election with no constituency poll — the rule was set at Clacton and it holds here. What the model can do without one is bound the plausible range from the 2024 result and the live national posterior, and then say which unknown actually moves the outcome. In this race that unknown is not the swing. It is who stands.
Projected shares
10th–90th percentile, median marked
Path to victory
Each row conditions on one field event, using the same draws as the headline number — so the probabilities are directly comparable to it and to each other.
| If… | Share of draws | p(Labour hold) | p(Green win) |
|---|---|---|---|
| Andrew Feinstein stands again: his 18.94% bloc keeps its name and organisation. | 45% | 83.1% | 15.0% |
| Feinstein does not stand: his bloc splits between a replacement, the Greens and abstention. | 55% | 81.5% | 18.4% |
| Green leader Zack Polanski stands: national profile, resources, and a squeeze on the left independent vote. | 25% | 55.8% | 44.1% |
| Labour's worst field: a national party leader against a local left with no candidate of its own. | 14% | 56.5% | 43.5% |
| Top decile of the left-revolt factor: simultaneous Labour demobilisation and Green mobilisation. | 10% | 56.7% | 39.8% |
The national anchor
The seat baseline is swung by the live U.K. posterior, weighted toward proportional rather than uniform swing: a bastion at 48.9% does not shed the national points the way an average seat does.
| Party | 2024 national | Model now | Swing |
|---|---|---|---|
| Labour | 33.7% | 24.4% | −9.3 |
| Conservative | 23.7% | 19.7% | −4.0 |
| Liberal Democrats | 12.2% | 10.6% | −1.6 |
| Reform UK | 14.3% | 24.3% | +10.0 |
| Green | 6.8% | 11.8% | +5.0 |
| Other candidates | 3.8% | 5.3% | +1.5 |
The field
Nobody has formally declared. The names below are reported intentions, tracked so that the model follows the field rather than a guess about its size.
- Zack Polanski Green Party reported intention
- Andrew Feinstein Independent reported intention
- Count Binface Count Binface Party reported intention
What happened here in 2024
- Keir Starmer Labour 18,884 48.9%
- Andrew Feinstein Independent 7,312 18.9%
- David Stansell Green 4,030 10.4%
- Mehreen Malik Conservative 2,776 7.2%
- David Roberts Reform UK 2,371 6.1%
- Charlie Clinton Liberal Democrat 2,236 5.8%
- Six other candidates 993 2.6%
July 4, 2024 general election result — 38,602 votes cast, 54.1% turnout.
Read this before quoting a number
- No constituency poll, no polling date and no candidate list. Three first-order unknowns; the intervals shown are the model’s, not the world’s.
- The probability that Feinstein or Polanski stands is a documented judgement, not a measurement. Those two numbers drive most of the spread, and any news about the field should update them before anything else in the model is touched.
- Starmer’s personal vote is stripped with a prior centred on zero and an undetermined sign. The 2024 boundaries are new, so the repo has no earlier line for this seat and no London comparator — the level is not identified, and the model refuses to invent one.
- There is no new-prime-minister honeymoon term. Burnham has been prime minister since July and the national posterior already measures him; adding a bounce would count it twice.
Methodology after the signal
A by-election model that says what it does not know.
The engine simulates flows from the 2024 voter blocs, swings them by the live national posterior, and treats the two candidacy questions as explicit events rather than as variance folded into a wider interval. That is what lets the page answer “what would change this race?” instead of only “what is the number?”
- Projected shares — run 2026-09-01 · 50,000 simulations · v0.1-fundamentals
- The national anchor — web_data/uk/latest.json