General election forecast
Swindon South
Predicted winner: Reform UK with 29.7% of the vote, a 0.4pp margin over Labour.
Predicted vote share
How the model expects this constituency to vote
Coloured number is the swing from the 2024 general election result.
Sitting MP
Heidi Alexander
- Party: Labour Party
- Tenure: 1.9 years (since 2024-07-04)
- Status: standing again
See also: TheyWorkForYou
2024 general election result
What happened on 4 July 2024
| Candidate | Party | Votes | Share |
|---|---|---|---|
| Heidi Alexander | Labour Party | 21,676 | 48.4% |
| Robert Buckland | Conservative and Unionist Party | 12,070 | 26.9% |
| Catherine Kosidowski | Reform UK | 6,194 | 13.8% |
| Roderick George Hebden | Green Party | 2,539 | 5.7% |
| Matt McCabe | Lib Dem | 1,843 | 4.1% |
| Martin Costello | Independent | 472 | 1.1% |
Source: Returning officer declaration
How accurate is the model here?
Our 2024 backtest for this constituency
We replayed the same model architecture against the 4 July 2024 general election using only the data a forecaster running the model in May 2024 would have known. Here's what it would have predicted for Swindon South, and what actually happened.
Predicted
Actual on 4 July 2024
Positive gap = we predicted that party would win more share than they did. See the full GE backtest across all 650 seats for the model's national accuracy.
How this forecast was built
- GE2024 Baseline. Actual GE2024 result in Swindon South
- National Swing (Strong Transition Model). Multiplicative bounded swing, losers shed in proportion to local share, gainers absorb pro-rata national gain. Replaces additive UNS.
- BES MRP Prior. Baseline blended with BES Wave 1-30 south_west prior at weight 5%
- English-identity floor. English 27.5% → Reform +1.0pp
- Normalise. Shares scaled to 100%